Found it on the internet
According to the manual the FB sends and recieves on channel 16, when you send a PC message over this channel you’re able to change it to your custom channel. Very cryptic and yes I did lead to funky behaviour already. But did we expect otherwise?
NAME:FB2
OUT:A
CHANNEL:16
PITCH: FREQ1
PRES: FREQ2
1: FREQ2
2: RESO2
4: FM
5: ADSR_A
7:INPUT
11: AM
16: ADSR_D
17: ADSR_R
18: AR_A
19: AR_R