Greetings Bill:  In my experience with leather and wood, the hot glue
is best because it will not cause damage to either of the two
materials.

An excellent book, "The Aging of Organ Leathers", is available about
the why and how of leather failure.  The Organ Literature Foundation
and the Organ Historical Society both carry it if memory serves.
A key cause of early leather deterioration sited was exposure to an
acid.  The exposure need not be lengthy to break down the fibers in the
leather.  The concentrated acetic acid released as the sealant dries
should theoretically shorten the leather life substantially to my way
of thinking.

Silicone compounds are also notorious for being hard to remove.  Wood
given a silicone "wax" treatment is a real problem to refinish.  I
would think that the silicone seeping into the pores of the wood and
traveling along the grain would make the next rebuild a terrible job.
I have had to throw away actions that have been treated with various
silicone products and my opinion is that no valuable musical instrument
should come in contact with any silicone product.  Natural products all
can be removed easily and reapplied easily so they make for
authenticity and less of a problem for the next rebuilder.

Al Sefl - Only using GE silicone sealer as hair gel on his toupee...