I have old docs and stuff from the forthcoming FF7PC Techdoc I can dig out. I can't do it right now, but maybe in a few days.
But yeah, the Script was what we never figured out. Cosmo handles Dialog, backgrounds/Palette, and music, mainly.
The SaiNt's figured out some more (not sure if he wants them made public), and I've done a little with another section.
Trouble is that, IIRC, the PC field files are mostly different than the PSX ones. For instance, isn't the way backgrounds are stored completely different?