Hi Chris,
I'm sorry for my delayed response. Just wanted to let you know that I've been working on this, but I haven't had time to write down how to do this. I've encountered a bug introduced in the latest version of Kiosc, which causes the feedback of the button to not work properly. This will be solved in the next release of Kiosc, which I guess will come in the next couple of weeks. You can activate and deactivate a Kiosc button by sending a bool to it, just like you did before with the Indicator I guess.
Then, there is CueluxPro. I ran into a bit more issues with this. After the update from Kiosc, it should be possible to select and deselect the first 64 fixtures using Kiosc messages. Please note that this does not include subfixtures. For subfixtures you can use the groups instead though. Or you can create custom fixtures instead of subfixtures. These custom fixtures could have the first two custom faders in use for the two relays for example.
If by changing the physical appearance of the button you mean the colour, I'm afraid you will have to wait for an update of CueluxPro. Although I do need to do some more testing, so it might be possible just yet. It is possible to send a colour using OSC to a button, to change its appearance. Unfortunately to have this trigger on a fixture being selected or deselected, we first need to finish the implementation of the trigger flank for this. I don't think that is working properly now. When this is fixed, you could setup two actions for each fixture, one for when it is selected (send a colour) and one for when it is deselected (send a different colour)
Like I said, I still have to test a bit more. Can you tell me how far you have gotten with this?
Greetings,
Bootsy