Thank you for trying the game. In particular, thank you very much for reporting the gamepad quirkiness. I have only tested it with a SNES style gamepad. Perhaps I should make a button configuration screen.
About the color: I deliberately make it a bit cryptic so that the it does not scare people away. But well, because you ask: I can tell you Sprechstunde's weak point is red and Geburtsjahr's is yellow. Let's say, Hund (dog). Its is blue. And when the German people write them with their article, they are die Sprechstunde, das Geburtsjahr, and der Hund.