Faction-dependent CTD: help needed!

This problem has been observed in the process of adapting the provincial campaign from RTW 1.2 to 1.5.

I'm able to start the campaign and play several turns with 10 of the 13 playable factions.
However, the other three cause instant CTD when the loading bar arrives to the end after selecting the faction in the provincial campaign menu.
Those three factions are greek_cities, germans (converted into Celtiberians) and britons (converted into Celtic Spanish tribes).

The CTD happens also when playing with another faction and a character, for example a diplomat or spy, finds a greek settlement or character.
Some of the things I've tried:
- to eliminate the new models/textures used for strat map, but CTD.
- to keep all the original buildings associated with the barbarian and greek cultures, as fas as possible,

It is strange because there are some other barbarian (spain, gauls, dacia) and greek (thrace, seleucid) factions in the game, so it cannot be some culture associated problem.
In strat map, the only different things are banners (not for greeks), and models (in some cases).

Any idea to solve this problem?:san_huh:
Could it be associated to some incompatibility between region owner and culture tag?:san_huh: