After sorting my feedback for the different pinned topics, the "left over" that I was going to post in "First impression" was almost all on the UI and related stuff. So figured it'd make more sense to make a thread for that instead of using the "First Impression" one.

Ordered mostly by how early in my playthroughs it annoyed me:

Notifications should show what I got from curiosity

When collecting a curiosity I get a pop up on screen and a notification in the bottom tray thing. The notification should show me what I collected. The unite that moved might not have been in focus, so at times I got no clue if it was food/gold or science or how much.

Readability of tooltips/tutorials

I'm really not a Fan of the seemingly Random Capitalization during the Tutorials. I know it's that every game concept starts with a capital letter, but words like turn and battle isn't really specialized for this game and it's distracting to read. 

Also could we maybe change up the "Icon Name " format a bit? I much prefer the way you've done numbers to how the other things are handled. 

Ex: "Three (3) Rounds of Battle are played every -> Turn". The () around the 3 helps to show it's the same information shown in a different format. The turn icon should get the same treatment. So "Three (3) Rounds of battle are played every turn (->)" (wrong turn symbol, but closest I got on the keyboard)

Closing tutorial messages

Lots of tutorials are impossible to close without using the eye symbol in top right. Which by the hover text seems to remove all related tutorials too. Either it's bad hover text or we need a "OK" button to only close the current one.

Please let me drag to reposition tutorial pop ups

They keep hiding information I'm actually looking at. So I either need to start caring about whatever the tutorial wants to talk about now, or close it and never learn that bit.

Let me move it out of the way and/or maybe minimize it somehow.

Culture selection screen

Would be nice if the "more detailed" culture screen would remain open when I scroll to the next one. So I don't have to keep reopen it every time. Lot of extra clicking

"Culture Chosen" Notification

The "Opponent moved on to next era with culture x" notification isn't great. First of "Franks moved to Medieval Era with Franks". Only tells me that somebody moved to Medieval and Franks are no longer open. I need information on who they where and a name that doesn't change. So that I know who we are talking about.

The "Locate the event" button here doesn't work as I'd except either. It should either take me to the Capital of that player, into diplo dialog with them or show that culture. Probably the last one. Currently it takes me to the list of next age cultures, which I can't really interact with and doesn't help me.

Selling of resources

Opponents buying resources grants me a one time gold bonus, doesn't it? How much? I can't seem to find this information anywhere. Should probably tell me in the notification if nothing else.

Does it gives me any other bonuses, like ongoing gold income or something? Beside the gold from some buildings/Infrastructure that counts number of trade routes.

Emblematic quarters

Please have them show up in build list of cities as a greyed out option, both before I got the tech for it and after I build all available copies. Mouse over could then show what tech I need or that I already got one in every territory, beside the normal information. This way I know its neighboring bonuses etc, both for planning before tech unlock and placing new neighbors after the fact.

Opponent names

Notifications of changes to relations/trade etc reference the culture name, but since that keeps changing I don't know who is who. Everyone need an unique name that doesn't change. Show this and the current culture and maybe in that opponents color. A more "human friendly" name than AI1, AI2 etc

Resource icons on map

The icons showing luxury and strategic resources are always shown. I would really like to be able to hid this, same as with the FIMS toggle.

Wonder/Holy site production time

If you move these out from the top of the queue, it show infinite turns to complete. All other constructions shows the turns to build everything up to and including it self as the "to complete" counter.

Detailed tooltip

The detailed tooltip has a tendency to hid the "default" tooltip. To the point I'm often not sure where I'm even looking at atm. These need to be better at not obscuring other information and probably be smaller in general.

Open diplo dialog

The buttons for the different opponents in top left should have a tooltip showing culture and unique name

Right clicking an opponents cities or units should also open the diplo dialog

Autosave

If you select something other then saving every turn, the autosave function doesn't save on turn 1. It probably should always start on turn 1 and then skip appropriate number of turns going forward.

This seems the most appropriate post to add my observations on user interface.

Notifications:

+ Generally much improved compared to what I had seen before. For instance, we now know which era stars were earned, or who bought what resource from me.

- However, more work would still be useful. For instance.

- "A foreign war has been declared" - who declared it on whom?

- AI's attitude towards me has changed. From what? Is it an improvement or a deterioration?

- It took me a while to find the impacts from the osmosis events. I think it would be more obvious if it were displayed above the city, similar to how gains from ransacked animal sanctuaries are handled.

Maybe notifications, maybe map, but the yields from curiosities still disappear way too quickly. Treat them like battle outcomes that stay until clicked away, or like the notifications from pillaging animal sanctuaries.

Game map

- It would be nice to show altitude, along with yield tool tips, just for the avoidance of doubt how altitude behaves.

- It can be hard to read at a glance what type of terrain a certain tile is and what yields it gives. Civilization does that better in that, even there these is less clime variation, you know instantly what a terrain is and does. Flat grasslands = 2 food. Here, not always so clear, so I'm more reliant on the FIMS overlay.

- Similarly, I can't immediately distinguish the types of quarters. They look too similar from a distance. Maybe fewer, but more prominent buildings on the quarters and more extreme use of colours would help. For all the flak it got over art style, Civ VI did that fairly well in my view.

- Maybe fits better under city screen, but I wasn't quite sure from the outset how exactly natural wonders work. I'd make the description more explicit that the benefits apply to any city in that territory (or having that territory attached to it) and that it does not need to reach that wonder via an exploitation.

Tech tree

- It would be nice to show within the tech tree the industry cost of units that are unlocked with a particular technology.

- For unresearched tech, the iconography of what an unlocked item is, is unclear. You have those nice hexes, squares etc., but they're not much use of we can't see them against the same-colour background. One the tech is researched, it's much clearer, but then it's also too late.

City menu

+ The effects of placing districts has been much improved. It's great to see the little before/after values for each tile affected.

- At the same time, I would leave the old value consistently to the left and the new to the right. I find it slightly confusing for it to display in a different sequence for the negative stability effect of a new quarter.

- It would be useful to indicate somewhere whether quarters can be attached to an item or not. I was wondering that for extractors, harbours, holy sites, wonders etc.

- Similarly, whether the construction exploits just its own tile or those around it. Or, for that matter, an even farther range. I didn't realise harbours had range 2 until I started placing them.

- Maybe more of a bug, but when viewing tile yields for an Egyptian pyramid, the line for that description breaks and the next line doesn't indent properly. It slightly interferes with the quality of that tool tip. That may well happen for other tile yield impacts with long names.

- The list option for the building menu is a nice idea, but I would prefer a boring of "names + turn" numbers approach there, rather than mini icons. Just for the avoidance of doubt and not having all icons in our heads.

Independent Peoples

- I encountered a bug that messed with the display of how much influence I had over them. It tended to display the influence from whatever other independent city I had selected previously.

- It would be good to know how high the effect of a praise would be before activating it and how long it would last for.

- I would reorder the benefits received for different levels of IP relations such that the added benefit of the next higher level is always added at the bottom. That would make it easier to see what's different. At the moment, these are often inserted into the middle, so it becomes less clear.

Diplomacy

- I'd want some differentiation which diplomatic modifiers count for how much. Could be qualitative, if we want to maintain flavour. But I would strongly assume that some things weigh more heavily than others, so please show us!

- As mentioned elsewhere, I'd really want a breakdown of their ideology and how it compares to mine. See the other thread for impacts of ideology.

Other

+ I really like the little fame progression bars that appear when we get close to a star.

- At the same time, such progression bars might be quite nice in the main fame star menu. Little visualisations help.

+ I like how events and civic choices now show the position on the ideology axes before and after a choice. But I was often not quite sure what's the before and what's the after. I think those two need to be made more distinct and obviously old/new. I guess a more strongly coloured or filled box could more clearly represent "future state".

- Bug: there is broken help text under the ideology quick menu (i.e. not the civic screen, if I remember right).

- I found some of the help texts appearing repeatedly after I had already turned them off.

- Edit: one more thing: when selecting cultures, I'd want the unit descriptions to give numbers to any bonuses. I picked Greeks with hoplites and only after I had them (or even in the battle?) did I realise how big their formation bonus was. I'd want to know that was I assess cultures to pick.

- Somewhere, we should have a record of what cultures they had previously adopted. Maybe in the treaty history? Maybe that can be rebranded into a diplomatic history, to capture all things that occured between those players.