David P. Wright argues that the variant reading in 2 Nephi 8:19 (= Isaiah 51:19) is in error and an impossibility in Hebrew.
David P. Wright, “Isaiah in the Book of Mormon: Or Joseph Smith in Isaiah,” in American Apocrypha: Essays on the Book of Mormon, ed. Dan Vogel and Brent Lee Metcalfe (Salt Lake City: Signature Books, 2002), 166-67
In one case where the BoM has another word for an italicized one, the meaning is significantly changed, but not in accordance with the Hebrew original. The phrase “These two things are come unto thee” becomes “These two sons are come unto thee” (Isa. 51:19//2 Ne. 8:19). This is an extremely unlikely reading for any ancient text since the phrase in Hebrew is formulated in the feminine (šětayim henna qōr’ōtayik) whereas “sons” (bānîm) is masculine. The variant in the BoM is oblivious to the requirements of Hebrew, and is doubtful that the Hebrew developed from a masculine to feminine formulation. Smith apparently replaced the italicized word, picking up “sons” from the context of vv. 18 and 20.