Thanks for the update and information. I'm not really sure if I can do something about SDL, but I will have a look and see if I can do something.
I still need to double check a couple of things to be honest. I can not seem to find the right controller configuration for playing on SteamDeck using an external controller. If you're playing on the the SteamDeck using SteamOS maybe it would be easier to enable Proton for now and use the Windows build to play. At least, until I find a stable and viable long term solution.