In 2021 Stanford Carmack published his findings relating to relative pronoun usage. He summarizes:
This study compares personal relative pronoun usage in the earliest text of the Book of Mormon with 11 specimens of Joseph Smith’s early writings, 25 pseudo-archaic texts, the King James Bible, and more than 200,000 early modern (1473–1700) and late modern (1701–1800+) texts. The linguistic pattern of the Book of Mormon in this domain — a pattern difficult to consciously manipulate in a sustained manner — uniquely points to a less-common early modern pattern. Because there is no matching of the Book of Mormon’s pattern except with a small percentage of early modern texts, the indications are that Joseph Smith was neither the author nor the English-language translator of this pervasive element of the dictation language of the Book of Mormon. Cross-verification by means of large database comparisons and matching with one of the finest pseudo-archaic texts confirm these findings.– Stanford Carmack – Personal Relative Pronoun Usage in the Book of Mormon: An Important Authorship Diagnostic
If Joseph Smith was “neither the author nor the English-language translator of this pervasive element of the dictation”, where did the Book of Mormon come from?