In answer to the idea of using silicone RTV for work in piano
repair, I'd say definitely not!  Silicone sealant/adhesive cannot
be completely removed, and nothing will stick to cured silicone.

Silicone adhesives and sealants have their uses; they're perfect for
semi-transparent structural adhesive for glass curtain walls, etc.,
in buildings.  I glued a very heavy piece of broken glass pendant onto
the bottom of the remaining piece on an antique chandelier: 10 years
counting.  I've glued broken curved greenhouse glass: 30 years and
counting.  Boating folks absolutely abhor the silicone sealants when
they discover that they can never remove the stuff from the part or
the fiberglass.

Go online to any of the manufacturers of silicone sealants.  Some will
discuss adhesive 'debond' solvents but most say that you must replace
the glass.

The advantage of hot glues is that they can be renewed, washed off,
and the surfaces are ready for regluing.

Douglas S. Heckrotte
Philadelphia, Pennsylvania