I have an add-on which listens for “Ctrl+Alt+T” shortcut using commands API. It works fine with English (US) keyboard layout, but does not work on the other (Russian in my case). However built-in shortcuts (for example Ctrl+T) do work on Russian layout, so I believe it is a bug.
I think some keyboards send a different code for left and right of some special keys. Does it matter which side you use for Ctrl or Alt?
All 4 combinations of l/r ctrl + l/r alt + T work on English layout and none work on Russian
You can file a bug on: https://bugzilla.mozilla.org/
Done: https://bugzilla.mozilla.org/show_bug.cgi?id=1782660 . Thanks for guidance!