I don’t know whether annealing helps, but I did once see an etched
bowl where the depth of the etching appeared to vary according to
where the metal was and was not work-hardened by the sinking process.
One thing that I have incorporated into my etching protocol for
silver is to etch the silver briefly (one minute in nitric acid)
after cleaning but before applying the pattern. I find that the
etching causes the ink to adhere significantly better than any kind
of scrubbing, sanding, etc.