Oh hey! This is a thing. Now that I've been converted into CP, I'll help test some of your civs out too! I'm definitely going to end up focusing on earlier-game ones mostly because, well, it'll take me forever to test out later stuff. But yes, I'm like to start with say...the Papal States (though CulDiv doesn't seem to be properly in order with CP to super mega push religion as them) or maybe Flanders (if the Belfast thing is fixed with Neuschwanstein...assuming that even still does the same thing, I think it actually might not anymore). Possibly Germans too. I will report back to you when I see how they all gel!
Edit: Played a little while as the Germans. Everything more or less worked as intended, just a few oddities.
1: Most noticeable but actually the least real problem is simply that all the icons for the upgraded Tribal Villages show up on the select screen and DoM, as is wont to happen with EUI. I am pretty sure people, maybe even yourself, have adjusted that to work right for other civs, so it should be simple to fix.
2: Tribal Encampments seem to be available to be built on any non-resource location, not simply forests and jungles as intended. I think CP alters terrain coding in some way, so that's liable to be it.
3: Mostly matters relevant to the tech tree. The Slaganz obsoletes at Bronze Working, I imagine since the Spearman is its new upgrade, but by default all units in CP become obsolete at the tech of the upgrade after its next one - so properly, it should obsolete at Civil Service instead, IIRC. Or maybe Steel, the way it handles Swordsmen is odd IMO. In a similar vein, the techs where you can upgrade to Tribal Villages are a bit off since Metal Casting is now in the Classical Era but Guilds and Civil Service are all the way at the end, after Chivalry. I can see why it might be appropriate to have the Iron-giving one a bit earlier, but I do know the intent was to have them all at equal points on the tech tree. Personally I'd actually recommend moving the other two back to Classical since Medieval is a liiiiittle too late, but that's your call really since you probably had them at the early Medieval for a reason.
4: I'm not actually sure if this is a bug or not - just that if German units pass through a Barbarian camp, they can actually disband it without doing anything to the units inside. It just seemed odd to me but I can see why it might actually be that way on purpose - say, for CS quests which early game are almost always clearing barbarian camps, so that diplomacy early on isn't solely a lost cause (after all I kind of see the Germans as a major-civ-angrying defensive civ more than anything, CS alliances would make sense to have). Might also be a thing with Leugi's Barbarian Enhancements. I didn't ever get into a war so I don't know if I'd actually get all their Generals for myself, I definitely ought to test that part out as well.
5: Getting ZOC on barbs, which I know has nothing to do with CP but just something I know is still a thing. Don't know if that's on purpose or just something difficult to deal with - i imagine if it's literally a hard-coded 'you are no longer in war state with barbarians' matter then you shouldn't be getting ZOC'd, but I do know the game handles barbarian diplomacy weird so I can imagine if it's not actually like that but just making them have no combat strength against you or something.