Multispectral imaging of the original manuscript for land(s) at the beginning of the manuscript line indicates a faint s; thus the original text seems to have read lands here. Oliver Cowdery’s virtually immediate correction of the singular land to lands in the printer’s manuscript (there is no change in the level of ink flow) seems to be a correction to the actual reading of 𝓞 rather than the result of editing on Oliver’s part. Elsewhere in the text, there are eight instances that refer to the “possession of lands”. There is nothing wrong with the plural lands here in Alma 58:38.
Summary: Maintain in Alma 58:38 the plural lands (“we are in the possession of our lands”), the apparent reading in 𝓞 and the corrected reading in 𝓟.