Technics KN6500 & Midi

KN6500 & Midi
Earlier this year, I posted a plea for some assistance to allow me to re-live my experiences from the mid-to-late 1980s, using my first Technics keyboard (a KN600) with my Atari ST and some sequencing software called “Breakthru’ 2” by a UK company: Gajits. Roger Mepstead from the Technics 7000 support team contacted me and was very helpful but he advised that he could only help up to a point. Invaluable as his advice was, I am now looking to move on to the next stage.
I want to prepare song files that allow me to run a backing whilst I play my Technics 6500 as the main performance. So, I want to produce a file from a sequencer application (I plan to use Cakewalk by BandLab) that operates bass, guitar riffs, etc. to replicate a commercial recording and play along to this. The backing will be played on my old Technics KN800 and an even older Roland CM32L sound module. The Midi connections will be via a USB interface.
I propose using the Cakewalk “Staff” input screen (a music score sheet which accepts step inputs) to build my song file and now here’s my problem. I have set up my midi system as in the diagram attached and would like to know if it will deliver what I want.
Finally, I believe I need to instruct the sequencer to activate particular voices on the various sound modules and wonder if I have to set up the Technics keyboards to achieve this. Can anyone help, please?