I think the toggle and hold sustain buttons are labeled backwards. Unless I just don’t know what sustain means, which is entirely possible, pressing space doesn’t seem to toggle it, you have to hold space. And you don’t need to hold right control to sustain, you just need to toggle it.
Steps to Reproduce
Use a piano, try to use one of the sustain things.
What I expected to happen
Space to toggle it, right ctrl to only do it while held.
What happened
The buttons did the other things.