and there are a few necessary location changes (@Pavía please split Szeged from Csongrád, it's one of the most important Free Royal Cities of this period and an important stop on the Transylvanian Salt Road
I totally agree. Szeged was and still is very important. Devs should create a new one from Csongrád and Makó and name it Szeegd.
I'd like to present my proposal for a better location split in Hungary as well, in addition to your Szeged and Csongrád split.
The Kecskemét and Cegléd split. In my opinion, the red circle should be the rough outline for Kecskemét, while the pink circle should be the rough outline for Cegléd.
According to Nándor Ikvai's 1982
Cegléd Története, page 88, the city was mentioned in a charter in 1444 as a city. Furthermore, it could choose its own judges from 1420 and was allowed to hold its own markets from 1448. Ikvai cites page 88 of László Makkai's
Pest Megye Története from 1961, as well as records from the Hungarian National Archives. I think, considering that many historical maps show Kecskemét's extent to be oriented towards its west and east, this might be a worthwhile redraw for better accuracy. Do note that this would give Kecskemét a Cuman minority as there are several Cuman settlements to the west. The remaining land from Jakabszállás should be renamed to Félegyháza, while Kiskunfélegyháza gets renamed to Halas.
As for the yellow borders, I think that could be a new province. Now, it's fine if you keep it as it is, but I have a preference for natural borders where its possible to achieve them. So, in my opinion, Kalocsa and Solt shouldn't be a part of Fejér (with a J, not with an H.) The northern bit of Solt looks like a part of Csepel island, which I believe should be owned by a different location. Nowadays its more meaningful cities are closer to the capital and to Székesfehérvár, so it should either be owned by Székesfehérvár or Buda. It's probably okay to keep it as it is now