how do i get the romanian monarchy achivement

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like i give up transyvania to hungary and stuff

[Targyisplaying]

Can't help very much since I haven't tried getting that achievement, but according to Joker Maximus' guide (see it here https://steamcommunity.com/sharedfiles/filedetails/?id=1408297198), you have to go authoritarian as Ion Iliescu and get as much nationalist as you can. In fact, don't give Transylvania up to Hungary, but ruther supress the Hungarian minority. At some point an event will fire giving you the option to crown king Mihai.

Hope that helps you. If I discover how to properly do it, I'll post it here so it can help you and others. Cheers!