@rva-818x-laystar Don't use 'Reset' from RetroArch's menu, since it will disable any configuration done by RetroPie - including the BIOS folder used as 'System Dir'.
Rename the retroarch.cfg file from the pcengine folder or delete it, then re-install the emulator before starting any PCEngine games. Re-installation will re-generate the RetroPie's default configuration for pcengine.