Is there anything (short of removing and starting over) that can be done to eliminate the dreaded "silvering" effect encountered when [stupidly] applying decals to a flat paint surface?

Someone on Hyperscale suggested I use Tamiya thin cement to alleviate the silvering..(put plastic glue over my paint & decals? Yikes!)...followed by an application of Dullcote.
Well...it ain't perfect - like ANY of 'em are, right? - but it's better than it WAS. Huh! Who'd a thunk it?
That's one of the things I like about this (or any other forum)...there's always somebody out there [that's been there, done that] who knows more than I do - which ain't all that hard to do. lol

Try spraying gloss varnish over the areas to be declled , then when they have dryed, spray with matt/semi matt or whatever finish is required. Decals adhere better on the gloss finish and are easier to move into position.

If you already applied the decals and they silvered. You can try using a very fine sowing needle to prick the decals' surface (where it silvered) about 5-7 times in a broad area; add a drop of white vinegar to the decal surface; let dry 24 hrs -repeat if needed; when the silvering disappears then seal with a flat coat. Keep the decal on the horizontal when adding the vinegar and letting it dry.