Exactly! I became aware of this when I installed the mod Reconquista TW. I tried to play several campaigns but the game always crashed around the year 1150. The province naming of the mod and the VI campaign is the same ("ID_LANDREG_01"), and this was the cause of the CTDs because the event of the fairs of Champagne appears around 1150 but the game engine didn't find the region "ID_CHAMPAGNE" in the startpos file. You can test it if you change the start date of the VI campaign to 1140 for instance (and also the end date to 1453), and you will see how your VI campaign will crash in a few turns.