Hey Devourer.

Despite the CTD you're experiencing happens only with eastern factions, the reason does not necessarily have to be culture related.

Armenia, Parthia and Pontus share a lot more than culture, like units, maybe formations, etc...

Removing those three factions from a culture may not be the solution and it can involve a lot of work (and a perfect opportunity to get more bugs).

My advice is still to check this thread.