Did you spray on a layer of Dullcote before weathering? Or Microscale decal film? If not, I'd suggest doing that.
If you did, I'd have to guess that maybe the overcoat sis not fully cover or that something did not fully dry before weathering. Once the decal is overcoated and all is fully dry I don't see how it would get through albeit maybe the turpentine affected it.
I don't know. Most of the decaling I do nowadays is with ones I print but I do use others and still use Solvaset. I don't put a puddle on and allow the decal to lie flat while it drys; I always have the items being decaled at an angle pretty close to vertical so the Solvaset runs off
The only dedcal solvent I let dry with the decal flat is when using Micro Set (Blue). I use Micro Sol (Red) and Solvaset pretty much interchangeably as they seem rather close in strength. Of course, new, just opened bottles may seem stronger but ....