"right mouse click" from keyboard

Seems that would be entirely dependent on the specific keyboard, the driver used, the settings, the OS, etc. Most keyboards don't have such a key at all of course. But if yours has such a key, and it can truly ne programmed to send a signal that an application would see as an actual right mouse click, then I assume it would work. Might well require a lot of fiddling to figure put how to configure it that way. Seems to me that's so much a MuseScore question as one for the keybiard manufacturer, whomever makes the driver for it, for the OS, etc.