John W. Welch discusses the occurrence of the Aramaic terms "mammon" and "raca" in the Book of Mormon.
John W. Welch, Illuminating the Sermon at the Temple & the Sermon on the Mount (Provo, UT: Foundation for Ancient Research and Mormon Studies, 1999), 172-73
Only a few passages require discussion in regard to the Nephites' ability to understand what Jesus was talking about. The first instance is whether the Nephites would have understood the word mammon. The ancient origins and etymology of this word are highly uncertain. Around the time of Jesus it was a frequently used Aramaic word in Palestine, meaning "wealth, property, profit, or money," appearing in the Targums, the Mishnah, the Talmud, and the Damascus Document. It is unknown how far back in history the word was known or where it came from, and thus one cannot be certain about the nature of its occurrence in 3 Nephi. Aramaic is old enough that a Nephite word for money could have been "mammon," but without access to the original Nephite texts it is unclear if Jesus used this Aramaic word in the Sermon at the Temple, or if it was a part of Nephite vocabulary, or whether Jesus used some closely comparable Nephite word for "wealth" that was simply translated by Joseph Smith as "mammon."
Nevertheless, the context of laying up heavenly treasures and serving only one master makes it clear what Jesus was talking about. Similar things can be said of the Aramaic word Raca, whose antiquity and possible derivation from Hebrew is also uncertain but whose basic meaning is unmistakable in the context of calling another a fool in ridicule or derision.