My cache folder in ff7 folder is empty.. so of course no effect deleting it. Materia's textures always return back to originals installed with bootleg
FF7/mods/bootleg/cache/menu
any time you make changes to the mods folder you will need to clear this cache.
there is also a cache is the main ff7 directory, not entirely sure what the difference is, most things are cached to the mods folder, but some things will go to the main cache.
There is another thing you should try also please, Manu>>>go to bootloader and uncheck compress textures, clear cache. Load the game up and open the menu system, go to materia menu, close game, recheck compress textures. Now you will have the other Materias or you can throw an egg at me. Same process to go back. I forgot about that step...