The Book of Mormon is remarkable in that it introduces 188 names. We would reasonably expect that if Joseph Smith had created the text himself then some of these names would be out of place, anachronistic or from the wrong region.
Interestingly we find the exact opposite. In fact none of the names that are unique to the Book of Mormon include consonants that do not exist in Hebrew.
The Book of Mormon Onomasticon notes that:
Of 337 proper names in the Book of Mormon, 188 (about 56 percent) are unique to the Book of Mormon. That is, they occur in the Book of Mormon but not in the Bible.
Apart from King James English spellings of biblical names in the Book of Mormon, the letters F, Q, V, W, X, and Y do not appear in transliterated Book of Mormon nouns. The one exception is the /FF/ in ZENIFF and ZIFF. This exception could be explained by an aspirated final /p/.
F only appears singly in one such noun which is familiar from the KJV (LUCIFER), but never begins a proper noun in either Bible or Book of Mormon.
V only appears inside such nouns which are familiar from the KJV (EVE, LEVI).
W only appears inside one such noun which is familiar from the KJV (JEW, JEWS).
Y only appears inside such nouns which are familiar from the KJV (MARY, SYRIA, TIMOTHY).
Q and X do not appear at all, in either the Bible or Book of Mormon.– Book of Mormon Onomasticon – Fun Facts About Our Onomasticon
What are the odds that none of the names unique to the Book of Mormon contain consonants that do not exist in Hebrew? How would Joseph have known to avoid these consonants?