In a significant number of instances, where there are differences, the differences in the Book of Mormon agree with these ancient texts. Was Joseph just guessing right?
Let's suppose for a second that the reality was the exact opposite of this. Let's just suppose that John Tvedtnes's arguments for agreement with ancient texts are exceptionally weak and are better explained in terms of KJV modification. Let's further suppose that in at least the vast majority of cases, the modifications to the KJV text have no discernable relationship to the underlying manuscripts and further that the Book of Mormon preserves KJV translation errors from underlying texts in instances in which it is in agreement with the KJV text.
Let's just pretend - for a second - that this is true.
What do you think it would mean? Obviously, you assert the opposite, but if this were true, what would it mean?