Upvote:1
You are allowed to apply in any embassy (US case). But according a consular officer, this is often not well interpreted, if you do not have good reason to do it. It could seems that you look for the less strict consular office (and if I read correctly your question, it seems that first interview was not so good, so ...). In addition the Polish embassy may have more problem to understand your school system, and to read/translate the documents.
So you can do it, but unless it is very unfavourable, I would try to get to Kiev.