Currently in the game there are several different ways to win: Score, Elimination, Expansion, Economic, Diplomatic, Wonder, Scientific, Supremacy, Quest, and Shared victories. I will be going over each one, settle over their pros and cons and why they are unbalanced.

Score- The highest scoring faction at the end of 150 turns wins, however this is unbalanced with how much "empty score" is currently in the game. Military is weighed too much in terms of score. For example making 6 low tier units and deploying them can easily boost your score by 50 (My solution make military score much less)

Expansion- Possibly one the hardest victory types; Possess 80% of regions. Which in most cases is downright impossible to achieve. Might as well go for a Supremacy victory which is much easier. Some factions just don't really expand well and playing against an aggressive player would never allow for this type of victory in its current state. (My solution make the victory 50% of regions)

Economic- A very niche way too win, achievable by most but broken lords and roving clans excel at it. Honestly its very balanced amongst the factions and a very viable victory type. (My solution don't change it)

Diplomatic- Currently Diplomatic is the easiest and most unbalanced way to win for any faction (except necro) Ive looked into the values and it takes about 950 diplomatic points to win a fast victory. Currently the game does not have good scaling options for diplomatic it is easy to achieve through any speed and map size with ease. Currently the values for diplomacy are

Unknown, Cold war, Truce, and war = 1, I think all these values should be 0

Peace = 2, This value is honestly fine but should be taken down to 1

Alliance = 4, This is what really sets up diplomacy for an easy victory, should be 2

Although the accumulative score isn't the issue the issue is making trades which multiplies your current score with the player by 10 and adds it to your overall score. (If the values above changed to what I suggested there would be no reason to change this multiplier... Or just keep the values the same and half the multiplier.)

Wonder- Similar to quest victory except much more achievable. This victory once you reach the final faction quest you will be prompted to build the "temple to the earth's core" Which takes 36,000 industry, 40 mithrite & 40 hyperium to build. This is honestly very achievable by any class (This quest is fine although should be changed to 25 of every resource to be alittle more possible to people without native resources)

Scientific- Another incredibly hard victory to obtain due to poor scaling right now scientific victory requires 5  of the 6 techs to be researched. With how rare science in board can be the victory can quite difficult to achieve, each tech requires about 40000-60000 science each to research and all together requires 200,000-300,000 total which is an insane amount. (How I would fix this issue? Make science victory only 2-3 techs required)

Supremacy- Simple premise; control each enemy capital. The person with the best military wins (No need for balance)

Quest- Same as wonder just a bit more difficult, complete 6 specific faction tasks to complete the game (Never attempted this victory since I've always gone for wonder but I can assume it could need class specific balancing)

Shared- The lazy mans victory just be in an alliance with someone who get victory and you win.

Currently these are my takes on the currently victories in the game if you have any suggestions or something that I got wrong feel free to leave feedback.

I think a lot of your issues with the pace of victories are realted to playing on fast speed. For better or worse the game is meant to be played at normal speed. A lot of these become much easier or difficult depending on speed of the game. 

I know most players who play casual multiplayer prefer a faster game and often play at fast speed but i highly recommend finding a group that can play regularly and doing a normal speed game...even if it takes 2 seasions to finish. You may find vicyoru pacing more to your liking. 

I think it's odd that on fast speed production cost is 50% but resource gathering is only increased by 1.5x (instead of 2x).  This makes things that cost resources more expensive to build relative to standard speed.

Also, xp doesn't double either so quests that require leveling a hero to 4 (for example) take twice as long relative to turns compared to normal speed.  I wish they had just made all resource gathering, FIDSI, exp, and movement 1.5x for fast speed.  I think that would have been better than the unusual modifications they chose.

Ok, let's see.

1. Score - this victory type just limits number of turns, nothing more. If nobody can get science, economics or other victory types(example - from turn 30-40 in game left only 2 oppoents, who constantly at war with each other and can't stop producing units).

2. Elimination.

Pretty simple victory type, if you already got better economy and managed to kill some players. 

3. Expansion

Simular to elimination.

4. Economic.

One of 2 "main" victory types. Ofc, vaulters and ardent mages are better at this.

5. Diplomatic.

As for me - most unfair victory type, because one time I got roving clan without any city(only setseke) and who got this victory. But, still victory.

Without +1 from cold war and war - you just can't win a game. In multiplayer one you are reach 90% - everyone will get a alert and they wil break all relations with you.

6. Wonder.

Pretty cool victory type, but sometimes realy hard to get. Main problem with this victory type - quests doesn't scale with game speed. So, if in quest you should wait for 5 turns - that will be 5 turns on any speed. That is pretty bad.

7. Quest victory.

Very hard to get. But still an option. So, why not.