FF4 assets aplenty, was there a hack?

I've been browsing the sprite database and the custom song repository and I'm noticing there's a lot of FF4 content in there.

Was somebody making an "FF4 in FF6 engine" hack?  Is it for crossovers like Dark Sorcerer?  Or is it just that FF4 was wildly popular?



...I've been toying with the idea of simulating a dark wave with Swordtech, having each of the eight versions do greater damage but with a bigger backlash.  It was really just a thought experiment, but I wonder if there would be merit to exploring an FF6 expression of the Lunarian struggle.  Has someone done this before?  I know there were attempts to depict 1 in this engine that didn't pan out, but again I'm curious if someone tried it with 4.