I do think the Pula, Croatian and Dalmatian coast needs some love.
Yes, but sadly, that would have to be another mod. Balkans is a restricted zone for me. I don't hate myself enough to open that Pandora's box
In all my research; I could not find a source map for the vanilla De-Jure that was from before 1498. I did find this one:
I apologize for leaving it as a link. I could not find a better source for this pic which I feel is the best of both worlds. It resembles the vanilla De-Jure(reducing work) while making it possible to map counties and duchies in a way that resembles Roman Pannonia but also hints at later developments.
and for once more back to Hungary:
Here are little more detailed comparions.
First a better one where I used the 13th century map posted above:
Most of Hungary is really surprisingly close to those borders. Some places like the Netherlands would dream to be anywhere near this close to the actual historical borders.
Now, I forgot that I also do have a map of the first known counties as they existed in the 10th and 11th centuries. Here it is compared with the CK3 map:
it makes it clear that those borders which looked weird on the later map do make sense in the 11th century perspective.
Outside of Transylvania, there are exactly 2 small historical counties, which are missing on CK3 map. Some borders may look weird, but that changes when we put back those 13th century borders and add the 1090 map of Hungarian dioceses you repeatedly mentioned.
From the combination of these 3 maps, the biggest breach of historicity seems the provinces of Eger and Heves, whose borders I adjusted in order to better fit a situation as depicted on the map I showed few posts above, which had Eger as independent county, which has disappeared already during the 11th century. Most of other differences are slight simplifications or things, which would require adding and/or moving a barony from one county to another. No big crazy changes, no big flux you spoke about.
To be honest, with this comparion, Hungary's counties seem far more stable than almost any other part of the map, and the CK3 depiction of the situation seems surprisingly accurate.
So now, you have it put all together. Could you please now show, what a map modder should do to make a better setup of medieval Hungary?