Hi
The byte just before the end byte F7 is the checksum
The simplier way is put z5 as byte in the sysex editor of the modulator
It’s strange that THRU and off are the same param
On my roland 0n/off and 00:THRU are 2 different params
strange that length of sysex is different for the same param
it looks like you just have to put f0…xx z5 f7 in the sysex editor
may be you could rely the quneo to the daw (cc) and ctrlr to mc909 (sysex&cc)
that way you control the mc with quneo