Here's the tuning file

Practically speaking, where are you taking those extra keys from? I have considered extending the number of assignable note key shortcuts before but it didn't seem practical at all given the limited number of available keys.

For 31-edo, I was thinking of assigning Q-\ as notes 0-12, A-; as notes 13-22, and Z-. as notes 23-31. This fits the C-to-C scale on the keyboard while removing the negative note numbers.

For 53-edo, assigning some sample of notes across the scale (for example 0/4/9/13/18/22/26/31/35/40/44/49/53) to the keyboard and using the transpose shortcuts to reach the other notes could work. Adding the note numbers to the command names in the settings would help here. I imagine different people would have their own preferences on which notes to include for easy access.

I think the natural extension of this idea would be to allow assigning arbitrary note numbers to keys. In the 53-edo example, using only 12 assigned notes per scale, you could fit 2 octaves on the keyboard if you allowed assignment of notes -53 to 53. Allowing assignment of the full -64 to 63 range would make for a really long options menu, but that might open up options for other tunings.

I made an account here to suggest the same thing! I sometimes use a custom 19edo keyboard layout and almost all the keys can be bound but still a few are out of range. For EDOs larger than this, if you have a tuning file with all the possible pitches, you might not have enough keys on the keyboard to keybind them all, but the ones you do bind still need to be in range, which is limiting.

The range could be expanded in either direction; if keys could be assigned below Base Octave C, then my layout could start at Base Octave -1 A instead, so that the Z key would be assigned Base Octave C, and the highest note, backslash/pipe key would be Base Octave +2 A#. Or if it was expanded upward, then my layout could start at Base Octave C and go up to Base Octave +3 C#.

Attached is a picture of the keyboard layout and what keys can and can't be bound. Thank you so much to the developers for making such a wonderful tool for xenharmonic music! :)

19edo keybinds.png (118,668 bytes)   

19edo keybinds.png (118,668 bytes)   

As of r20224, available shortcuts now go up to base octave + 4 B. Please give it a try, as it hasn't been tested very much. You can download test builds from https://builds.openmpt.org/builds/ (should show up in a few hours there) or set the update channel to "Development" (ditto).

I'm able to assign a full 31-edo C-to-C scale to different keys using r20224. Thank you!