Indeed, ArM2 addresses already, just how Hermeticism and the Order of Hermes are connected. I think we had that from catnip & garlic on already.
ArM2 Houses of Hermes p.28 introduces the Seekers and the Legend of the Old Ones. p.30f has a hectoring Arch-Mage with the 'trust-inspiring' name Infamitus expound it. Both thereby put Hermeticism in perspective wrt the history of the Order of Hermes.
The Order of Hermes was founded chiefly by magi who had descended from the Roman cult of Mercury, which in turn took its wisdom and knowledge of the mystic powers from the Greek cult of Hermes. The Seekers, a group of magi who investigate the past in search of the origins of magic, believe that these ancient Greek wizards had some contact with those beings known to the Greeks as gods. Evidence of wizards in ancient Egypt and still more ancient Babylon suggest (sic!) that even the cult of Hermes was a descendent of a previous order from the early history of the Mediterranean cultures. Again, these Egyptian and Babylonian sorcerers, say the Seekers, had contact with what the commoners called gods who taught them the basic elements of a theory of magic. Any history as to the origin of Babylonian and Egyptian magi, however, is purely legend. The Seekers call this "history" the legend of the old ones.
((sic!) mine)
The Seekers are magi from the Order of Hermes. They are not among the founders of that Order. By HoH:TL p.15 their early champion is Lucian, first apprentice of Trianoma, who contemplated to form an own line of Bonisagi after 836, and was told off by Notatus.
Hermeticists are quite likely among the Seekers, and campaigns where a discovery by a Seeker converts the Order of Hermes to Hermeticism are certainly possible.
Cheers