Hello. I recently used the converter in its latest d'Este release, using latest version of both CK2 and EU4, and found a curious thing in terms of culture conversion. I played as Hispania and the provinces in the Asturias state, which were all Castilian, became Galician. Not only that, but also they got the Galician kingdom core in all of them. The problem is that the actual CK2 title was held by someone who didn't had land in that area, neither was it part of de jure k_spanish_galicia. I'd assume the cores got assigned first, then the provinces' culture were changed based on that, but why it happened in the first place is the problem. Since at least from what I saw, there was no reason for those Galicia cores to be added there.
So, yeah, reporting this. Thanks for your attention.