[yunohn]

I think the majority of English speakers are completely unaware of this meaning. “Proctor” on the other hand, is something they would’ve heard of in an exam setting.

[festive-minsky]

Mabye I'm in the minority; I'd never heard of a "Proctor", but I have heard of a "Proctologist", which is an anus doctor

[scbrg]

Is this one of those regional things? Is the same word used throughout the entire English speaking world?

Not a native English speaker myself, so my association was to the Greek word as well.