We do know that there are non-American regions in the Matrix (e.g. we see Japan in the Animatrix story Beyond, and Mount Everest is one of the locations for the short story System Freeze), so surely at least one red pill was recruited from one of these non-American locations (even if we don't see any such red pills).
I can't think of any red pills that are definitely not English speaking and/or culturally American, but we don't know if that's the case for all the red pills. Based on the list of Resistance characters on the Matrix Wiki (note that not all of these characters were born in the Matrix, and some aren't even human), the best candidates for examples of characters which might come from a non-American culture seem to be
- Sawayaka (real name Jayna Kiyomizu, possibly Japanese)
- Vashuo (real name Anatoli Ivanov, possibly Russian)
These characters would speak English to their fellow Zionites, but they may speak their native language as well. In addition to these characters, there are also better known characters which speak English but might come from a non-American cultural background (e.g. Jue, Vector, Binary, etc.).
It appears that Zion does recruit primarily from English-speaking, culturally American bluepills. Or, at least the films just focus on Zion's activities there. This is probably due to the fact that
- it is easier for Zion to recruit from people who share the operatives' culture (which is predominately American)
- the Machines appear to have concentrated the most important parts of the Matrix within culturally American parts of the Matrix (the Oracle lives there, the Agents took Morpheus there when they captured him, the nuclear power plant that was destroyed to help Neo travel to the Source is there, etc.)
- Neo is American, and the story focuses on him. Although there are possibly other Zion ships operating in non-American parts of the Matrix, we the audience are following his ship in areas familiar to him.
The cultural dominance of the United States within the Matrix can in turn be explained by the fact that
- the simulation is set to 1999, a time in which the United States was the sole superpower in the world.
- Machine ambassadors in the real world met with human ambassadors at the United Nations, which is headquartered in New York City (seen in the Animatrix story The Second Renaissance). NYC was the seat of the humans' power in the real world, so the Machines used its cultural influence as the basis for most of the Matrix and especially its important parts.
We can probably rule out other, non-American Zions in the real world as that would counter the Machines' system of repeatedly destroying Zion -- they would have to destroy the other Zions, too, whereas it's easier to just destroy one. Also, in the 100 years of fighting the Machines, presumably the "American Zion" would have stumbled across the "non-American Zion(s)".