The ones that have used those particular paints will be ale to answer better. But if the surface is glossy then o need, I don’t think, to Future. Being silver, any silvering should be at a minimum but it can still happen.
I look at the paint being merely a color layer, not what kind of surface it has, and I usually go through the whole process before I decal. I don’t use much in the way of glossy paint and so far the only thing I have not needed any gloss coat on is Alclad. But I do give the whole thing a couple of coats of clear after decaling to help hide the carrier film.