Hi John,
I search with the search function (Cmd + F) in my PDF reader program for "reverse cymbal" in the Genos Data List, starting on page 24 (Drum/SFX Kit List):
In "ElectroKit", "AnalogKit" and "DanceKit" there is a "Reverse Cymbal" on Note #28 (key E0).
There should be also the voice "Rev. Cymbal" in the "GM&XG" folder, sub category "Percussive" (#000-000-120). ("GM&XG" voices are still in Genos, but not listed in the "Data List".)
A "Rev. Cymbal" voice should also be in "GM2" folder, sub category "Percussive" (#121-000-120).
Note: "120" is the Yamaha Program #, the MIDI Program Change # is 119.
Best regards,
Chris