Although Jesus does not specifically tell Israel about the people of the New World, he does give them a hint that there are those of his covenant people who are not in Israel. Jesus notes the language we have in John 10:16 where he described “other sheep.” Why does he give this information to the twelve?
The twelve now know that they will not be reunited at any time soon with the rest of the house of Israel. However, it would be comforting to know that while the Father commanded that their presence not be explicitly described, they were yet brought to the possible consciousness of Israel. They were not forgotten while Jesus served his earthly ministry in Israel. Israel through their stiffneckedness might not have understood, but Jesus did.
Translation: The entire section on “other sheep” relies upon the New Testament context and the culturally familiar aspects of sheepherding. Jesus is the shepherd, and brings his fold together. These images were obvious and present to the people of the Old World where a common occupation was sheepherding. However, there were no sheep in the New World, and it was obviously not a common profession. As with many of the sayings in the Sermon on the Mount, what we have is the New Testament vocabulary laid over the content that would have been presented to those in the New World. Jesus certainly communicated this information, but would have done so in a way that would have been more readily understandable to his Nephite audience. However, the audience for the Book of Mormon would be more familiar with the New Testament imagery, and it therefore is more appropriate in the context of our modern translation.