"if it's a y it's Ukrainian and if an i it's Polish" is one of those many RULES OF THUMB, but nor necessarily a hard fast rule.
Staying flexible is key in this kind of research and I would like to complement you for doing as well as you are, even w/o the language skill. ___________________________________________
GC seminarian studies in Galicia Province > Austro-Hungarian Empire did not necessitate a PHD in Theology, as is required today.
In that time frame the avg rural education for a villager was three grades, and they were lucky to get that. You are researching very much of a feudal type system that outlasted Western Europe by a few centuries, well into the 19th century. _______________________________________
"local assistant" could be the deacon ???
Suffix A on surname is just female version of surname. If ending w/A appears on male surname, you can assume Polish heritage in most cases.