Hi @resonotter, thanks a lot! This sounds like the device is going to be usable indeed.
The default setting for the buttons on CS X51 is to send note on/note off. Pressing the topmost button sends note 60 with velocity 127 when pressed, and note 60 with velocity 0 when released. (I should note here that my Midi knowledge is not deep, but at least this is visible in the Midi monitor.) Looking at your patch, the following is a first step:
With a pipe that takes Midi in and immediately sends it back out, the buttons light up as long as they are held down. Adding a filter to block Note off, the buttons stay lit after being pressed. However, toggling on gets me only halfway there 
Perhaps this is what’s been discussed in this thread. Did you solve this kind of problem in your patch?
EDIT – user error alert! It turns out that contrary to what I was thinking, the CS X51 editor does in fact work, and with toggle functionality. I’ll proceed from here, and report on progress 