I'm wanting to use fusion with multiple resource packs that utilize a system of individual textures and map them together on the blocks the way optifine used to. e.g. textures name 0 through to 5 for a 2x3 pattern resulting in connected textures similar to the continuous option that fusion has. Attempting to convert these over to fusions single texture to cover multiple blocks would be a monumental task that I don't feel many resource pack makers would be willing to do. "just use Syntra and Continuity" is the usual response.

It would be amazing if the option to edit the existing, or add to the mcmeta files, that could utilize existing resource packs current folder and texture structures opening fusion up to greater compatibility overall.

If I understand correctly, you want to put each tile from the continuous texture into its own image file.
That seems like far more of a hassle to work with to me than the existing format where it is just all in the same image.

I overall just don't really like the structure and formats of OptiFine's resource pack features and I am not trying to replicate that.