Actually I do not know what's going on in this thread because I don't speak french, but someone in https://forum.recalbox.com/topic/21601/bluetooth-problem-in-rb-7-0 told me to post command output over here.
So I hope the following will be helpful for somebody, even if it doesn't seem to be related to my bluetooth problem:
# sdl2-jstest --list
error: failed to read gamecontrollerdb.txt: Invalid RWops
Found 1 joystick(s)
Joystick Name: 'usb gamepad '
Joystick Path: '/dev/input/event0'
Joystick GUID: 030000001008000001e5000010010000
Joystick Number: 0
Number of Axes: 2
Number of Buttons: 10
Number of Hats: 0
Number of B***s: 0
GameControllerConfig:
Name: 'NEXT SNES Controller'
Mapping: '030000001008000001e5000010010000,NEXT SNES Controller,a:b2,b:b1,back:b8,dpdown:+a1,dpleft:-a0,dpright:+a0,dpup:-a1,leftshoulder:b4,rightshoulder:b6,start:b9,x:b3,y:b0,'
Axis code 0: 0
Axis code 1: 1
Button code 0: 288
Button code 1: 289
Button code 2: 290
Button code 3: 291
Button code 4: 292
Button code 5: 293
Button code 6: 294
Button code 7: 295
Button code 8: 296
Button code 9: 297
Sorry if this is off topic - as said before, no french on my side.