So, my family history is my great grandparents came from what is now [a country that Reddit seems to flag as problematic as there is a war going on there now]... my uncle and cousin visited places from their childhood a few years ago. And a TA[from the shall-not-be-named country] back in college, when she gave us our names in Cyrillic on the second day, un-Americanized my name as for her it was a fairly common name.
But in looking in some scans through ancestry.com, I've looked at census data from 1930 as my great-grandfather's application for citizenship. In their reply to "What country were you born in" and "Do you speak other languages", they seem to have put Austria and German down. (Or, it was recorded that way; the scanned sheet does appear to be in a single handwriting). But when applying for citizenship, which I am assuming has more of a penalty for lying on, he lists his birthplace as well as my great-grandmother's as "Poland", and that he is renouncing citizenship from "The Republic of Poland"... this is 1923, from what I can tell.
So, all that said, I'm trying to square all this stuff into a single, sensible narrative. My main 2 Qs for this group, and I assume some may have an answer to one and not the other:

1. Have borders shifted between Poland and [the country to the east that Reddit seems to flag], so someone 100 years ago think of themselves as Polish and now we'd go there and it's in [That-U-Country-That-Shall-Not-Be-Named]?
2. As for the listing on the census that they were from Austria, that's not not even a shared border, so some thinking in the family is that post the Red Revolution, in midwest America in the 1930s, people would lie about being from [The previously mentioned former Soviet state now next to Poland]... does that make sense?