Hi
My family name is Mesesan and i am from Romania. Also, my great-grandfather and great-uncle came in US in 1912. I am not sure about the name Papp, it may be a Hungarian or the romanian Pop, which is very common.
As for Mesesan, it is definitely a Romanian name. I did some research back at home(I live in Transylvania). My grandparent's village, called Salajeni( quite a big village), in Salaj count is filled with people with this family name(Mesesan) that are not related. We are laughing saying that they had no imagination because they chose to be named after the nearby mountain: Meses.

i suggest you to start from here.When i asked my grandfather, he told me how poor romanian boys were taken to big hungarian towns and then shipped to america. it is a shot in the dark but worth exploring it: the birth and death book of the Orthodox Parish in Salajeni village.
Plus, you would get a chance to visit europe:)
i hope i was useful.
Best regards,
Catalina