@eroxx Recalbox was developed to play with joystick, to deliver an experience as close as possible to the original, we recommend using a keyboard only in computer games, which the keyboard was originally used for.

@zing thanks i found how to fix it. I can't update the recalbox on my arcade machine (that's the first thing i did when i received it and it buggued and couldn't reuse the sd card).

I just needed to go in controller and choose the input of each remote. It was really simple.

https://forum.recalbox.com/topic/26334/recalbox-8-x-on-rpi3

@RustyMG
I'm not sure I understand what you want, but see if it helps:
https://recalbox.gitbook.io/documentation/advanced-user/configuration/configuration-overload#exemple-2-mame

@KAZ01 if you know what you are doing, you can find libretro cores here:

/usr/lib/libretro