Have you checked the file “lightgun.cfg” on the system? It governs the controller presets for the automatic lightgun configuration and has quite a lot of notes and commentary which may help you here.

EDIT: the aforementioned file is actually on the Recalbox itself (forgot what folder) but here’s what I think is the latest version of the file viewable online: https://gitlab.com/recalbox/recalbox/-/blob/master/board/recalbox/fsoverlay/recalbox/share_init/system/.emulationstation/lightgun.cfg. You can search for the game name/platform and see what comes up.