UPDATE AS OF 1/20/24:
I think I’ve figured out where the problem lies on this issue. After doing some testing, I’ve discovered that if I use proton-ge-custom
(an unsupported AUR package, which I is apparently maintained by Glorious Eggroll) I have no joystick input into the game despite having joystick recognition at the system level, verified through the game controller settings as stated previously. This was the compatibility tool that was being used by Steam.
If I change that to Proton 8.0-4, my joystick works as it should. This is the solution I’m currently implementing. Note that this is with my system updated as of yesterday, not using the Snapshot I had rolled back to (from 1/10/24, pre-update). I’m not sure if the Snapshot was using Proton 8.0-4 or the AUR package as I didn’t check that, and I don’t plan to roll back to that Snapshot just to see.
I will notify the package maintainer of my discovery. Thanks for the replies.