The Book of Mormon uses conjunctions in other ways consistent with Hebrew, including as a replacement for the word “but”.
From John A. Tvedtnes
Another difference between Hebrew and English conjunctions is that in Hebrew the same conjunction can carry both the meaning and and also the opposite meaning but. Here are two well-known Bible passages in which the King James Version renders the conjunction but:
“Of every tree of the garden thou mayest freely eat: but of the tree of the knowledge of good and evil, thou shalt not eat of it” (Genesis 2:16-17).
“And as for Ishmael . . . I will make him a great nation. But my covenant will I establish with Isaac” (Genesis 17:20-21).
Evidence for Hebraism in the Book of Mormon lies in the fact that some passages use the conjunction and when but is expected. Here, for example, are two different versions of the Lord’s promise to Lehi:
“Inasmuch as ye shall keep my commandments ye shall prosper in the land; but inasmuch as ye will not keep my commandments ye shall be cut off from my presence” (2 Nephi 1:20; compare Alma 50:20).
“Inasmuch as ye shall keep my commandments ye shall prosper in the land; and inasmuch as ye will not keep my commandments ye shall be cut off from my presence” (2 Nephi 4:4).
In one of the quotations of this promise, Joseph Smith rendered the conjunction and, while in another place, he rendered it but. In other Book of Mormon passages, Joseph translated and when in English we would expect but because a contrastive meaning is clearly called for:
“And when I speak the word of God with sharpness they tremble and anger against me; and (= but) when I use no sharpness they harden their hearts against it” (Moroni 9:4).
“He commanded the multitude that they should cease to pray, and also his disciples. And (= but) he commanded them that they should not cease to pray in their hearts” (3 Nephi 20:1).– John A. Tvedtnes – The Hebrew Background of the Book of Mormon
Wouldn’t this kind of language be unnatural and unfamiliar to Joseph Smith?