I think parties that put revision as their cornerstone are kind of pointless. Like, this isn't something where your contrymen's support matters that much - what you need is huge international support and quite possibly a conflict you could abuse.

Around 1940 we basically needed Hitler to pull it off and that didn't last long. Closest I could

On the other hand, Fidesz is a big advocate for Transcapathian/Transylvanian autonomies, I think that's a much more realistic solution. And of course, later you can build on top of that. Them pouring money into surrounding regions, prompting Hungarians to stay there and grow is certainly an interesting move.