I know exactly why your census record said your Baiersky was German, even though your family has good reason to believe she was Polish.
It is all about Politics and Borders of the time. Keep in mind that at the turn-of-the century, Poland's nationality changed with the weather. I'll want to bet that your woman came from Prussia (old eastern Germany), which is now Poland.
I had the same problem with My Shultz. All census records said they came from Germany but that their parents' native tongue was Polish. Mine came from Konitz, Prussia which is now present day Chojnice, Poland.