Factory tuning must be done with the reeds exposed, and I’m pretty sure that’s what’s shown in the Hohner photos I’m remembering. I can’t think how else they would do it, and factory tuning on new Suzukis and Yamahas is pretty good. So my misgivings are probably misplaced. Your experimentation is certainly worthwhile. If it works, the lowest 3 notes or so might need further adjustment.