Every Christian accepts the Bible “as far as it is translated correctly”; nobody thinks a mistranslation is the word of God. Isn’t the Article of Faith unremarkable?

On its face, yes. The distinctive content comes from 1 Nephi 13 and from the Joseph Smith Translation, which revised the biblical text on the premise that content had been removed; that is a claim about transmission, not translation. The two sources are paired here for that reason: Article 8 sounds like ordinary caution, and the texts around it show that translated correctly carries a much larger claim about what was lost.