Well I guess I spoke too soon. Sega CD is indeed working great but TG16 CD is still not working at all…Not sure what to do since I have SYSCARD3.PCE in both the bios directory and the roms directory.

UPDATE: So yeah this last one was just my own oversight…I still have trouble remembering how intensely case-sensitive Linux is…

I renamed SYSCARD3.PCE to syscard3.pce and all is well…