What do you plan to mix the dye with, water or alcohol/spirit? Both will seep under the edge of masking tape slightly (not a lot,just making it look slightly ragged close up) but alcohol has a lower surface tension so will penetrate further. Concave curves are the worst for this as the tendency is for the tape to lift off the surface, whereas on convex surfaces the tension pulls the tape down so you normally get best results there. Best to apply the masking tape in the hollows last of all and immediately stain to guarantee maximum adhesion.

But as you’ve got some lacquer on the sides, any dye that gets through should sit on top of the surface, though it will sit in any dips in the finish. But it shouldn’t penetrate the lacquer, so you should be able to wipe it off again with water or alcohol/metho. Easier to do this before it’s too dry, so don’t leave the tape on too long after the main stain is touch dry.