The printer’s manuscript has the plural sides in the phrase “the wilderness sides on the north”. The 1830 compositor set this in the singular since this is what we expect: geographically there should only be one side on the north. Elsewhere in the text there are three other occurrences of “the wilderness side” but none with the plural sides:
The original manuscript is not extant here in Alma 22:29 but may have read in the singular, which would mean that Oliver Cowdery added a plural s to side as he copied the text from 𝓞 into 𝓟. There is considerable evidence that Oliver frequently added and deleted plural s ’s while copying. See, for instance, the cases of border(s) and shore(s) discussed under 1 Nephi 2:5. In fact, we have one case in 𝓞 where Oliver initially wrote the plural sides instead of the correct side, and in that instance he immediately corrected his error by erasing the plural s:
In all probability, the original text read “on the wilderness side” in Alma 22:29.
Summary: Accept in Alma 22:29 the 1830 compositor’s emendation of the text from the plural sides to the singular side in “on the wilderness side on the north”.