There’s no mute/solo button yet in Cantabile, although you can go a long way towards simulating them with bindings (as you’ve been doing). Worth also considering muting instruments by disabling the MIDI routes to the instruments - that way any sustained sound (or held notes) will continue to sound until released, rather than being chopped off, as you get with bypass. Cantabile is clever about not leaving any hanging notes if you cut the route while there’s MIDI activity on it.
Brad has been contemplating adding mute/solo - have a look at this thread.
Neil