For what it's worth  , I never apply a gloss coat specifically for decal application .

If you can Micro Sol decals down over 1/35 Zimmerit and more , are the super-nano-micro surface irregularities upon the surface of a paint going to be an issue ?

Nope .

I've never had silvering with decals .

I think that has to be a failure in the decal . The adhesive is nonexistent or has been washed away where the decal doesn't bond .