I've been unable to find something about this question.

I was trying to set up some new banners for rebels settlements, when the settlement is empty or out of the sight of the units/agents.
After many attempts I succeded in puting the new banners in game, but I was surprised by the following result: (I've used images as they are quite self-explanatory)






Unless somebody can show me where this aspect is coded (any text file?) I'm now thinking that this "silly" question is hardcoded, as the game is using the original faction-to-culture assignation instead of the new one (descr_sm_faction).