You'd have to generate .XML files, figure out how the chart files are structured, re-generate those.
Then you need to somehow create interesting and unique songs from those pictures, perhaps an existing AI exists to do that, not sure if there are any APIs for that though.
The hardest part is actually making it work, if you want anything interesting to happen you'd also have to make it compatible with Haxe for it to actually generate new code, then compile it, and anything else you need for the FNF engine, overall it seems like a massive undertaking.
Edit: Thinking about it for a bit longer, how do you plan to make the charts from the songs and have them be accurate? And all from a single image, to remind myself, wow.