The 12 triples of Isreal had been scattered abroud since babylon, they never fully returned to Isreal. It was prophesied in the OT. The only people who were said to be scattered are physical children of Isreal.
And the twelve tribes is always a reference to the nation of Israel as a whole. Why then, is James using this term if his audience is only Jewish Christians? One has to explain it away rather than allowing the Scripture to be honest. I don't want to do that.