Good question. I thought not in examining them. But they’ve been sitting there under pressure for over 50 years, and it does make some sense in that it would be unlikely that pre-stamped pads could be aligned so well. I think these pads and gaskets might have some implications for your project, perhaps being printable. If we were seeing some of these features on a new melodica, we might regard them as innovations.
There are strips of a more ordinary kind of gasket material in the Pianica 32 and in the early Pianica 25. They have pretty much rotted away and fallen apart. But they were not there to help seal the air chamber, and don’t appear to have had any functional value. I’d say they are cosmetic, but why that on the inside of a melodica?