The Book of Mormon contains many anachronisms to the modern reader. Rather than rely on the simplest explanation that the author of the book made up the story. (No one has ever said Joseph Smith was not imaginative) they fall back on trying to explain that the text may not have meant what it said (Those interested on the explanations from the LDS perspective can visit the FAIR Wiki).
The Mormon people at Fair, like any other apologist, want to convince the reader that something might be true, rather than show conclusive proof that something is true.
The use of the word adieu in the Book of Mormon has often been criticized, although it appears only once. If the Book of Mormon is a product of Joseph Smith's imagination as many outside of Mormonism suspect, it is simply not an issue. It is common practice for translators to use more colloquial phrases familiar to them for stylistic purposes or because at the time it conveys a more accurate meaning. As far as anachronisms go, this does not rank high on the list of problems with the book.
Of far more concern is the use of the term Christian far before the term was used in Europe, and of course, before Christ or Christians came into existence historically. While this may be an example of the amazing prophetic powers of the Ancient American peoples that the Book of Mormon proudly proclaims to have existed, the anachronism is more likely the result of someone looking back on events he know has occurred and having a person in a story make them look like a prophecy (Vergil uses this technique in Book Six of the Aeneid.)
Perhaps the most pressing concerns to archaeologists and other scientists who are trying to verify the Book of Mormon is that the book mentions both horse and steel in the periods that it takes place. Horses died out in the Americas long before the events of the Book of Mormon and were not reintroduced to the continent until Cortez. Steel, however, was invented after the dawn of the Iron Age, and had the events then taken place in Europe, would not be a problem.
Because the Author makes it clear the Book of Mormon takes place in the Americas, we must assume that either there is evidence yet to be found of this, it was a translation error, or something else entirely was meant. If we apply the philosophical principle of Occam's Razor, the first explanation becomes the most likely.
The Smithsonian has issued a statement that it has never used the Book of Mormon as a guide for research on any projects. The letter which can be found online does not discount the book's value as a religious text, but sheds considerable doubt on the books historicity. Rather than evaluate the book on its value as a literal text, perhaps a better question would be does the Book of Mormon serve a religious purpose as an inspirational text and a moral guide? Such a question is subjective and entirely to the reader. It is likely Joseph Smith's translation of the Golden plates will continue to have little impact outside of the religion that he founded.
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