I think it is highly unlikely that this is a short-form although my research is limited. All I have are family stories that were passsed down, the accuracy of which I am not entirely certain. The story goes that the Puskas name originated from noble roots in the 15 or 1600s. There were two principal palace guards, the official guards of the King. They were knighted and given the name and title Puskas "fon", which is the equivalent of de in the French or van in Dutch. My grandfather was still using the title 25 years ago.
I am apparently related to both lines as my granparents were both Puskas', one from each line.
I have only a limited understanding of the relationship between Hungary and Yugoslavia but I know that unless your name goes back farther than the middle ages, it is unlikely that this is a short form. A variation perhaps. There are many Romanians in the area of Hungary that used to be Transylvania but I don't think there is the same close link with Yugoslavia.
I wish you the best of luck with your search and would be interested in hearing from anyone else that has more to add about the Puskas family. I am also just beginning my research.