Assuming you cleaned the plastic properly before applying the Tamiya paint, you should have no problem with decals. Some decal setting solutions will cloud Future, but a second application of Future after cleaning the excess solution away appears to solve the problem.
Personally, I’ve never had a problem with Future and Micro-set, or Micro-Sol. But I never leave excess solution on the model, and my Future has always been thoroughly (sometimes months!) cured.
I can ditto Ross’ confidence in Future, and from a slightly more reckless viewpoint. [:O] I sprayed on 3 coats of Future this afternoon on a Spitfire, and decaled it this evening. [:-^]
I used PollyScale Decal Solvent to zap the decals into submission.
Now- I’m certainly not suggesting you do as I do… I probably should’ve had more patience and given the Future at least a day… I was just bored. LOL
Suffice to say- you should have a good experience if you use Future as a gloss coat before your decals. Recklessness not recommended…