Cumans: if you want to have an eco bonus, you have to make your second TC in feudal, otherwise you have no eco benefits at all. i also don’t like the UT cuman mercanaries, but it is way better than first crusade and flemish revolution because you actually have to TRAIN the units
Lithuanians: I like the civ a lot, but i really don’t like the relic bonus. It makes the games with a Lithuanian player involved so weird and frustrating. Especially in team games; with the help from your team you basically always get the bonus attack.
Sicilians: Can do everything but nothing well enough. I think they should receive Thumbring to make their archer plays more viable. Also i despise both of their unique techs.
Burgundians: Flemish revolution is the most stupid thing in the game and should be replaced with something permanent (which fits the games philosophy). Castle age cavaliers are strange, but i get used to see it.
Tatars: don’t like free techs too much (Thumb ring, parthian tactics). besides that i really enjoy the civ.
Koreans: free armor is needed, but war wagons need some tweaks to rebalance that buff.
Khmer: i don’t like the team bonus. It can make scorpions super viable in closed TG maps like arena, black forest or amazon tunnel. this team bonus in combination with Celts, Slavs, Ethiopians and Chinese is ridiculous. They should change it somehow like they did with the old mangonel team bonus from Koreans
Vietnamese: make player locations the team bonus and imperial skirm a civ bonus for vietnamese.
thats it, that are my thoughts