Here's my best guess:
The game database for NSUI seems to be hardcoded into the .exe file. If you calculate the checksum for the ROM, e.g.
$ md5sum ~/Desktop/Legend\ of\ Zelda\,\ The\ -\ Oracle\ of\ Seasons\ \(USA\,\ Australia\).gbc
f2dc6c4e093e4f8c6cbea80e8dbd62cb /home/bryan/Desktop/Legend...