As far as I know just the keys. I had a UK keyboard on my first A1200 and swapped them out with the new A1200.net black keycaps with no issues. As long as they are the plunger style it should only be a key swap. And you'll only need to swap a few keycaps at that, the differences between countries are only about 7 or 8 keys if I remember correctly.
I saw this one on sale in these forums
https://www.amibay.com/threads/amiga-1200-keyboard-german-layout-100-ok.2442581/
Could try with that. Good luck!