@ James...I'll relate to you a conversation I had a few years ago with a Hungarian woman, a lawyer, in her mid-50s, obviously a person of some former education to get that far. This was in 2012 It was here in SF, her English was so-so, so we spoke in German, which she was fluent at, basically no problem for either one of us linguistic. We touched on the present day Hungary, the past, ie 1920. She said, "Trianon tut noch weh." (Trianon still hurts). Obviously, that woman is a nationalist, up to a certain degree, maybe not a much as our flag wavers on the 4th of July.
In terms of being punitive, justified or unjustified (that's moral question) and draconian, Hungary among the losers in WW1 lost more square miles than any of its allies, Why were there Hungarian linguistic minorities in the inter-war years in Romania, Yugoslavia, Czechoslovakia, ?
I thought it's almost 100 years (I know, a bit imprecise, 92 years) and "they" still are focused on that event. The basic question as you referred to "old boundaries" Romania got just about all of Transylvania, ie all those Transylvanian towns that American tourists see today, Sibiu, Cluj, etc.
When I went back for a 11 night trip to England in Oct. 2017, the breakfast girl in the B&B was from Romania, I asked her which part of Romania. She said the northern part. That answer told me she was from the former Transylvania when those major towns went by German names, likewise with Cluj, and figured she probably learned German too as well as English, which is why she was in a London B&B to improve her English. So, I asked if she spoke German, yes, some (more or less what I had expected), but English was much better and showed those former names....all true today.