Try updating the gamecontrollerdb.txt inside the celeste folder. It's at 2.06 but my recently purchased USB controller from amazon didn't show up until 2.09.  The file is located in the executable dir.

update here: https://github.com/gabomdq/SDL_GameControllerDB/blob/master/gamecontrollerdb.txt...

Hi. I made this alteration in the gamecontrollerb.txt file as you mentioned, but the game still doesn't recognize my generic usb controller. =(

The best answer I found was: make your own stream of configuration. =)

https://www.generalarcade.com/gamepadtool/