Here the printer’s manuscript and the 1830 edition disagree on the spelling for the name of the Nephite governor. 𝓟 has Lachoneas while the 1830 edition has Lachoneus. However, the earliest occurrence of this name is in 3 Nephi 1:1, and there both 𝓟 and the 1830 edition have the u spelling, so Lachoneus should be taken as the correct spelling. The 1830 typesetter consistently spells this name with the u. Oliver Cowdery’s spelling in 𝓟 is usually with the u (12 times, including the case in 3 Nephi 1:1), but twice the a shows up (here in 3 Nephi 3:1 and also in 3 Nephi 3:22). In three other cases in 𝓟, Oliver’s vowel could be interpreted as either an a or a u (in 3 Nephi 3:2, 3, 24). The ultimate difficulty is Oliver’s handwriting: his u’s sometimes look like a’s and vice versa. For more on this point, see under 1 Nephi 4:35 (where the spelling for the name Zoram is discussed) or under Mormon 6:2 (where the 1830 spelling Camorah is compared with the manuscript spelling Cumorah).
Summary: Maintain the spelling Lachoneus for the name of the Nephite governor; the earliest occurrence of the name (in 3 Nephi 1:1) has the u vowel in the printer’s manuscript and in the 1830 edition, both firsthand copies of the original manuscript.