Hello HiassofT ,
sorry for the delay (I was occupied by my job).
Today I tested the new 8.1.0 and the remote (with my modifications in Lircmap and remote.xml) works fine. Also the PVR works fine again, but since I also switched from VDR to TvHeadend I do not know if this was related to the involved versions.
So this topic is solved.
Thank you very very much for your really great support and help!
Best regards, Nico.