It would depend if the game maker decided to include German as an option on their NTSC version, which I think it would be unlikely given Germany is a PAL territory.
Alternatively for gamecube games you can try holding down whatever key is mapped to "B" on the gamepad when starting the game to show the 60Hz prompt (if the specific game supports it).
Alternatively for gamecube games you can try holding down whatever key is mapped to "B" on the gamepad when starting the game to show the 60Hz prompt (if the specific game supports it).