Might need to see some screenshots of the former display problem - no, I've not come across it. You get display problems when something has not been coded in for a new culture - like the diplomacy messages etc.

As for the CTD, sounds like the culture change has caused some problems with the old culture-faction assignments as build requirements in EDB. Remember that although the cultural terms may still make sense culturally the factions may not if they have been specified as a faction rather than the culture.

If you post which faction has been reassigned the new culture and post the edb section showing the problem building tree I might be able to see the problem.