I realize this is a few months old but I would just like to second this, Reicast seems quite unreliable and outdated (especially the lr- version). This system (Dreamcast) seems to be the only one that has issues. I'm running all the way up to ps2 on an 8th gen i3 with no gpu, no issues except Dreamcast.
Would love to see an lr-redream as an optional/experimental option to add to my x86 build.
Edit: I've managed to integrate non-libretro redream into my retropie install on linux with a self-executing script that reads my joystick-selection.cfg and automatically changes my controller configuration based on that. Unfortunately the scripts are pretty crude so there's not a whole lot to share as it won't be dynamic to someone else's installation. It was all a lot simpler than I expected. I'm surprised redream hasn't already been added as an experimental package.