The Book of Mormon purports to be a translation. Therefore, it stands to reason that the language into which it was translated is not the language from which, according to its very own claims, it was translated. The fact that Joseph Smith used words with a Greek etymology (e.g., “Christ”) does not mean that the word “Christ” was on the very plates of the Book of Mormon. For someone with a long career in languages, Packham really should know better.
“Alpha and Omega” in the Book of Mormon is an accepted English expression and we may view it as the best way of conveying the meaning of a certain Nephite expression to English readers. The purpose of a translation is to transmit meanings, not words. “Alpha and Omega” makes more sense and is more recognizable to English readers than the Hebraic equilivant “Alepha and Taw.”