I'm not happy with us being called Eastern European, because we aren't Eastern European.
Your knowledge is pretty bad, because you lack historical, cultural, political and geographical insight into this part of Europe.
In terms of geography I already elaborated my point.
In terms of everything else (history, politics, culture, etc.), it really bothers me that you're calling Prussia "Russian". I can't even put it into words.
It is the the birthplace of the Teutonic Order and the place where Prussia was founded, the force that unified Germany into one (your own country for God's sake!). The Prussian Eagle and most of your national symbols come from there. It's literally the birthplace of one of the founding fathers of liberalism and the Enlightment era: Immanuel Kant. Liberalism, Rationalism and Enlightment is at the core of the Western civilization. And you just call it "Russia".
I would kind of understand if it was an American talking, but Jesus Christ. You're German.