Vasious said:
Wisdom would be grand, even if it is "Just live with it"
The AGCEEP is a historical mod and it tries to simulate what really happened - which means that Hungary isn't supposed to survive. You'll have to be pretty good to prevent that from happening - but it's not impossible.
I'd start by opening up the Austria event files and taking a look, followed by the Ottoman and Hungary ones as well. They're often the best place to start. You can find them in the EU2\AGCEEP\Events directory. The ability to search the directory is also a big help!
EDIT: Let me try this again.
OTTOMANS: In 1520, the Ottomans get an event (19008) "Suleyman demands the keys to Hungary" in which they get cores on Hungary 85% of the time unless Hungary owns Bulgaria or is allied to the Ottomans.
Basically, this is a lose-lose situation for you. If you submit, you become an Ottoman vassal, Lajos gets assassinated, and Austria claims Hungary - not to mention the fact that you're an Ottoman vassal. If you defy Suleyman, you get the Battle of Mohacs event in 1526, which eventually ends in Austria claiming Hungary. Choosing John Zapolya
seems to be the best option, since it gives Austria the option (15% chance) of not pressing their claim to Hungary. There's a later event that suggests Austria will inherit Hungary wholesale on his death, but the event doesn't seem to get triggered - very odd.
So, you want to avoid the Ottomans claiming Hungary. Simple - make sure you either conquer Bulgaria from them, or you're allied to them, by 1520.
What happens if they don't claim Hungary?
In that case, in August 1526 Lajos dies, and you have to make a choice - give Hungary to the Habsburgs or fight them. Unfortunately for you, even if you choose not to give in, Austria can still press their claims on you, with an 85% chance of them doing so.
Conclusion: You're screwed. Short of conquering Austria and its various successor-states, you're only going to delay the inevitable claim on your rich lands by your greedy neighbours. OR you could save your game in late July/early August 1526 and replay the same month over and over until Austria finally chooses not to press their claim!
...In which case, in 1540, John Zapolya dies, and you have the same frigging problem...with, oddly enough, the same event occurring. Hm, that's got to be a bug. If that's really the case, then it shouldn't trigger - the game won't let you trigger the same event twice, AFAIK - and you should be free! After that, if you survived that long, you shouldn't be bothered by any more claims on Hungary - but you also won't get many (any?) events, either.
If it were up to me, I'd avoid the whole situation - but obviously it's not possible for Lajos to do so.
Good luck!