@Xavier I found a workaround to my use-case :-D
(so to use the PreenFm2 as a one-channel, note-split limited "percussion" module with the KSP drum seq mode and 6-voice Volca Drum on Ch10)
The trick is with the Note Scaling, setting two limiters that target volume
Mod
Note1 Midi Scaling: +Exp 35 Flat
Note2 Midi Scaling: Flat 30 +Exp
(numbers are arbitrary, but some 1-2 relation like this seems to work)
Matrix
Not1 -> -10 -> *Mix
Not2 -> -10 -> *Mix
This way the notes (volumes) are limited to approx 4-5 keys, so the 4 channels can be split into some 20-25 notes range, which is perfectly ok
Of course, the Osc needs to be on fixed freq
What I reckon is an issue with this is that the notes are triggered anyway (that are being sent to the other gear on the same channel), so it is probably problematic in regard to polyphony and note-stealing