FCB+uno requires either midi channel 1, or "all".
Just notice this remark. Actually this not correct, although it's probably undocumented :
The FCB + UnO4Kemper will detect the MIDI channel which the KPA uses, and automatically adapt its communication to that channel. So you can put the KPA on any channel, and the UnO4Kemper FCB will work without extra configuration.
I'm not able to retest this right now, but I will soon and if it works as expected I will update the UnO4Kemper documentation.