As to who those other "Green Arrows of the World" were,
some were named, and others had no other identification than the country they were from.
(And, yes, just like in "The Batmen of All Nations", criminals did capture and impersonate one of the international archers.)
As for the other bowmen used in this story, there were:* Ace Archer of Scotland Yard / Bowman of Britain
* Bowman of the Bush
* Phantom (of France)
as well as Green Arrows from Japan (Ace Archer of Japan?), Mexico, Polynesia, Switzerland, as well as at least two other unnamed countries of origin?
If only a writer like Grant Morrison wanted to use this concept and expand it further!