The "romset is unknown" error in FBNeo is not a bug; it is a feature of precision. Arcade emulation respects the exact hardware of the original PCBs. A single wrong byte of sound data can cause the game to crash, so FBNeo refuses to run incomplete sets.
If you're still seeing this error, would you like a step-by-step on how to use a DAT file to verify your games? romset is unknown fbneo fixed