I use word association strings to better define words. Think of volver in this way: volver - revolver - revolve.
Technically, volver could mean go back or come back, but it will depend on the point of reference. In this case, it's a third person point of reference, and we have no indication that the speaker of the sentence is also in the country of origin. If it was explicitly the mother telling the story of how her son "volvió a casa a vivir conmigo" (returned home to live with me), you could say "he came back home to live with me." But even in English it would be unusual to hear a third person narrator say "he came back to his country of origin." The narrator would say "he went back to his country of origin."
In this case, it's all about the frame of reference.
I agree with you. In normal English usage, "country of origin" and "original country" are completely synonymous. "Original country" is not wrong.
More closely "country of origin," but "native country" is usually a good translation to use.
Is there a difference between volver and regresar? Does regresar refer more to returning something that was borrowed?
Can "para" also be used for this sentence? Does anyone know the rules for using "para" vs "a" in that both can mean "to"?