Interesting. I don't remember doing that, but that doesn't mean anything. I don't remember a lot of stuff. It can be embarrassing. Sometimes I wonder what it's going to be like in 10 years, assuming I live that much longer.
Not to dispute the solubility of toner in acetone, but I wonder if the difference was the substrate. That test was done on plastic, while this one was done on paper. Clearly, there was a difference in results, I just wonder why. Maybe the solvent is acting as a surfactant. Dunno. Matters not. If it smears, it's NFG.
I didn't use lacquer for the test because I didn't want to mix up a batch just to put a streak on a piece of paper. Not that it's tough to do, but then you have to clean up after it. Anyway, I was thinking of the solvent rather than the solids as the problem child. But, you're right - if there weren't other solvents in the lacquer, it would be a solid.
In any event, I will concede that it certainly can't hurt to put a barrier between the decal and any subsequent finish, and that shellac is a fine candidate for that barrier.