On top of the other changes&ideas regarding Hungary&Vojvodina brought up prior, I have a few niggles about some of the territory transfer focuses. They're all tied together in a way.
But first, I think Vojvodina should be renamed to Backa (or Backa&Baranja, though Baranja is a single province here, or Novi Sad if you want to name it after the central city in the state with historical relevance). Vojvodina in that time would refer to the combined Yugoslav portions of Baranja, Backa and Banat. Since Banat is cut out, it's not really "Vojvodina", now is it? This isn't just being pedantic, since I believe this misunderstanding somewhat fuels the current spottyness in the territories being transferred. I understand the separation of Vojvodina was important for making historical borders possible, but there are a few ways to adjust this while keeping the historical qualities.
HUN:
- Reaffirm Territorial Claims: add West Banat to claimed state list.
- Demand the Vojvodina: should include the West Banat state.
This is pretty straightforward.
GER:
- Second Vienna Award: add Banat to the transferred state list if all of Transylvania is given to Hungary. Hungary's focus includes it, while the Germany's 2nd Award doesn't. (Also important to my proposed solution to the historical borders issue.)
- First Ljublana Award: add an IF that checks if second_vienna_accepted_all is set, if true THEN include West Banat in the transfer, otherwise the award only gives Vojvodina(Backa) to Hungary. Thus if HUN only has North Transylvania, aka partial vienna accepted was set(or nothing at all), they'll get the approriate YUG territories. Historic borders preserved!
Now obviously this has a hole, if you complete 1st LA before 2nd VA, you don't get West Banat even if you get all of Transylvania. To solve this add an event that checks if second_vienna_accepted_all is set+GER completed the FLA focus but HUN doesn't have West Banat and have it fire once 2nd VA completes. The event would allow West Banat to get transferred to Hungary if accepted, or is auto accepted. Whichever you deem appropriate. Call it Ljublana Award amendment or Unite the Banat! or sth along those lines (since you'd have the Romanian portion of Banat as a prerequisite). You're already dealing with fantasy regarding territory transfers at this point, so why not go a little further?
The one thing I'm not sure on is if you can check if a focus itself is complete.
I think that about covers it. Hope I didn't miss anything. This, alongside the already mentioned core additions to Hungary would be a nice way to polish off that already existing area of the game without needing to make new territories or stuff.