Might a Vendhyan be called '[something] Singh'?

Why not? It just means "lion" in Hindi, so if we assume that the Vendhyan language corresponds, there's no problem.
Although Singh is an old name, it's also a definitely Sikh name of the last few centuries. I was thinking about using REH's character Jugra Singh from "Black Talons" as a Hyborian Age character; since he is likened to a beast of prey, 'Singh' probably is OK.
Emirikol said:
Like "Khan" from that old Star Trek show right?


Trek geek mode on\

His name was Khan Noonian Singh. I think Khan was supposed to be as in the Mongolian title and it morphed into the character's name as Khan has such a more forceful ring to it.

Trek geek mode off/

I think Singh whould be a great name for a Vendhyan or a Hyrkanian.