So, I was just sitting around with a friend playing the Umbral Choir for the first time, and I find myself ahead in the game somewhat. Having nothing else to build, I decided to grab the TCB so I could get some of those sweet market taxes. Once done though, I noted the Market Place was now shown to be on a certain system... my system, the hidden system that is the only one I really have and I have to rely on it staying hidden and jumping around.

Out of concern, I asked my friend what system he saw the market in, and he confirmed my suspiscions, You can indeed tell what System the Umbral Choir is in, if they build the TCB. Now, this is only an issue in Multiplayer, cause the AI doesn't really know how to work with that information. But it does seem a touch... risky, and it would be a shame to deny a Legendary building to the Umbral Choir because it would expose them to the Galaxy!

Edit: Realised this might go better in the Ideas section, preserving it here for discussion's sake

I feel like it's just a flavor of high risk/high reward. There are some other ways to discover UC like if you have the Academy you can see where are they if they have a governor (but you may not assign a governor to your HS if you don't wan't to give away that info to the Academy owner). Scouting probes also might give away UC fleets positions. Minor factions disappearing means UC is nearby "healing" them. I kinda like all that stuff cuz you have means to suspect where they might be but still need tech and tools to actually discover them. I don't quite get why so many people think that UC meant to be completely uninteractive galaxy/empire wise. If you want to be a center of galactic trade please be so kind to step out to the light. If you wanna stay hidden keep your profile low then.

More than that i think notifications about your systems being hacked should be done in such manner that if you attentive enough you might see or guess that your system has been hacked. Like something of the sort of visual effect when fleets get intercepted could be visible if someone is hacked/hacking your system rather than plain YOU GOT HACKED/GET REKT/GET HACKED notification which just autotriggers defensive measures from you.