Technically correct, but unnatural. Maybe acceptable in poetry.

Not really. Questions usualy become normal sentences by removing question word -> if after removing the question word the sentence seems unntural -> the question was wrong in the first place

Kogo widzi ona -> Widzi ona (ERR) - > incorrect question

Kogo ona widzi -> Ona widzi (OK) -> correct question

Without any context - no, I don't think so. If it was a text, and this "she" was just mentioned (This is Joanne. She is looking through the window. Whom does she see?"), then it would probably be okay, but my personal opinion is that it shouldn't be accepted here.