With you using the custom OS I'd definitely try a smaller subset of ROMs using the free version to make sure it plays nice with LineageOS before purchasing a license, but yeah the metadata for ROMs isn't affected by this logic so if the app runs it should act correctly (assuming the file system calls aren't affected at all by your OS). Good system to try is Sega 32X since it doesn't really have many games at all you can import the whole system and still be under the 100 item threshold.