I have broken Tracks in Snow's tutorial three separate times in the exact same place because of changes to the input system. The first time was missing it as part of an API rewrite for the stand alone system. The second time was because Ren'Py 8 no longer auto converted key constants to strings. The third time was because I made a key configuration file to let people bind keys themselves and forgot to change the key display code to reflect that the input system was storing strings instead of key constants.
All of this to say, rebindable keys are good but also, thoroughly test your shit because that one part of the game that is slightly different than everything else, it will break. It will break so hard in the most ridiculous ways