Currently, FMODGMS can only read external files. I'll try to see if there is a way to play imported sound resources.
I guess this has long since gone irrelevant. But i thought i'd mention in case anyone else wants to find this out.
If you want to play internal sound files with fmodgms then you can write something like. Granted that the file is set to streamed_compressed in GMS
FMODGMS_Snd_LoadSound(working_directory + "song_name.ogg");