Cool!
Yeah, does look like some silvering there. Other than a good coat of gloss and lots of decal setting solution I don't know what to tell you.
Since they're already on you might be able to cut a few slits in the decals and then flood them with decal setting solution and hope and pray they suck down to the surface.
If all else fails I've had some luck with cutting the slits and then applying a little Future to them. If you get it right it will leak under the decals and then seal the gap between them and the surface getting rid of the silvering.