> If you do it daily, in-house, for your own products... you might just have the title "Art Director."

"Art director" seems accurate for what a skillful user of art generators with a specific vision does.

I have also thought that since people find "director" lofty (thanks to auteur theory?) and therefore pretentious to assume, one could borrow "producer" from Vocaloid: https://vocaloid.fandom.com/wiki/Producer (alternative front end: https://antifandom.com/vocaloid/wiki/Producer).