I’m fully aware that this might not be your responsibility, but I want to confirm if Resident Evill 3 works in RetroArch with mednafen-psx core. Resident Evil 2 works in last stable release, but not in development builds.
edit: solved here. mednafen_psx core changed at some point the required BIOS files for PAL games. Instead of scph5502 with CRC 4D9E7C86, it needs one with CRC was D786F0B9, I had one scph5552 with that CRC, so you can rename it to 5502.