Hi @Dominik,
no big deal. Your code was for the Respeaker Core V2, I have a Respeaker 6-mic array. I found this: ReSpeaker 4-Mic Array HAT Mycroft A.I. Skill (ReSpeaker 4-Mic Array HAT Mycroft A.I. Skill) and the developer says he built it on your work. So maybe her can point you in the direction of the problem? This works on the Rasp Pi 4.
Regards,
Stephen