We need some place to talk about your firmware, bp... There are some things that I don't have enough know-how to deal with that it would be nice to share and get opinions on, makes no sense to do it in this thread.
I don't know what kind of resources there are on github to discuss, I didn't see any forum at a quick glance. But I guess a thread here would do as well. I've started some wiki pages regarding the controller on the deskthority wiki.
That said, I've crashed the KB a number of times with the way I type. Something about the right shift and an all-caps word or phrase. Haven't pinned it down yet, for all I know I am transitioning from the left shift to the right fast enough to hit the bootloader.
This reboot condition can be changed quite easily, to include more keys, or to something completely different. Or just remove it altogether and use the magnet switch to reset the controller.
I think that my space bar switch is causing an occasional double space.
This I have experienced myself. With space in particular (only space actually I think), I don't know if the de-bouncing time needs to be increased perhaps.
Another interesting thing is that I can get the KB to register both Win keys and the Menu key as down by using them with the Alt-key. Either Alt can do it to any of the 3 Win/Menu keys. Hold Alt, press Win/Menu, release the Win/Menu, release Alt. This sticks the Win/Menu key. Releasing Alt before Win/Menu does not do this.
Nothing like this ever happened to me as far as I know. Honestly I'm not using the latest firmware much. I should probably update my regular keyboard to use it as well to see if I can catch any bugs. Keys sticking in firmware sounds very odd in general, since they should be released by themselves very quickly if not registering as pressed. An actual hardware error (bad solder joint) wouldn't really explain it either. That should rather make the key flicker on and off. I would guess this is an OS issue (or OS-firmware compatibility issue at least).
If you want to check this out I suggest that you use Aqua's Key Test.
I still suggest using a proper OS
No, seriously, that seems odd, and of course it should work on all OSs. I haven't experienced anything like that myself. I use the Gnome "Show Layout Chart" for testing purposes.