Huvius - pics of your Alexander Henry are ESSENTIAL for further comment!!

Is it percussion or a cartridge arm?

Regarding "stalking" safeties, I have always, as you, considered that they were a predecessor to rebounding locks (in quality rifles) as a safety device to prevent accidental discharge, at the half cock position

Logically, your comment that they would be better on full cock, so that only one movement is required to have the rifle ready for shooting, is very valid, but not the norm in these rifles.
All my pre-rebounding lock rifles have them at half cock

Manufacturers ( and hunters?) of the day always? had them at half cock

Alexander Henry, was at the forefront of modifications for the advancement of manufacture, (see his single shot rifles) so it is logical he was the leader of such issues, and maybe ahead of the crowd

On another point, my postings on other forums (forae?) have had little response, except that there is little or no info on exports to Nepal, but they must have been there, possibly to the Nepal Royal family - you may have a treasure!

Good luck in your shooting

Tony