That is the obvious mistake: Hungarian=Magyar
It is not a mistake. We say for "Hungary" – Mađarska and it is from Magyar. That is the same.
Magyars were only one ethnicity in multiethnical kingdom. They were not even the dominant ethnicity ( the leading ethnical element were the Germans, since the founding of a kingdom
I am not sure what are you speaking of. I am saying that Magyars created Hungary, that land had Vojvodina in it for centuries and centuries and then Serbs used their numbers and took Vojvodina from Hungary. Just like Sqiptars in Kosovo. Hungarians lost a lot of population in combat with Ottomans in that area and some have escaped in the hinterland just like it happened with Serbs in Kosovo. Germans started to rule when Austria took the "Pole" position against the Turks.