Spell Graphics Document

Nice work with this, the result looks great!

I can add a couple pieces of information about the 6-byte graphics properties. In the byte 1, bit 6 (0x40) is the MSB of the tilemap offset from byte 1. Bit 7 (0x80) determines if the graphics is 2bpp (if 1) or 3bpp (if 0). Like you mention, the 16x16 tiles don't get loaded directly from ROM, but rather from the 2bpp or 3bpp tilemap, which are at D2/C000-D2/DFFF and D2/0000-D2/5FFF. You can view these tilemaps in FF6Tools via Ability -> Attack Tilemap (2bpp) or (3bpp).

Also, for the animation frame data at D1/0141-D1/E988, the 2-byte format is as follows:

Byte 0: xxxxyyyy (x,y) position for this tile
Byte 1: vhtttttt v/h flip and tile index

Each frame is terminated by 0xFFFF *OR* when it reaches the next pointer in the pointer table at D4/DF3C-D4/F645. So if your frames are sequential you can omit the 0xFFFF terminator to save 2 bytes. For reference, the subroutines that load this data are at C1/9F61 for BG threads and C1/A0C6 for sprite threads.