Would you be okay with maybe a special link with one background with a watermark just so I can test it? Otherwise I could later buy the pack as long as you wouldn't mind accepting a refund if they do not work with the engine.
Late reply but unfortunately they are not so for now I decided to stick to a custom background pack made from a user on this site named "Low". I would recommend for Dreamdale to one day make a compatible ver of these backgrounds or even a new set for MV/MZ as there's a large market for people looking for fresh backgrounds compared to other assets like icons and sprites that a lot already know how to do or have a shop for.