@holmes I know it's not the same subject, but in the documentation about configuring controls, it mentions another way, have you taken a look?
/recalbox/configs/mupen64/mupen64plus.cfg-
Mupen stand-alone and 4/3aspect ratio
Emulator Arcade/PC/Console • 19 Feb 2022, 22:43 • holmes 28 Mar 2022, 22:50