The earliest text here reads “if it were his desires to dwell in the land”. As discussed under Mosiah 18:10 and 18:11, the original text allows the plural desires in existential clauses, as in “if this be the desires of your hearts” (Mosiah 18:10) and “this is the desires of our hearts” (Mosiah 18:11). Here in Alma 17:22, the 1837 edition changed the plural desires to the singular desire (the same 1837 grammatical change was made in Mosiah 18:10 and 18:11). The critical text will restore the plural desires in Alma 17:22.
We also note here that the 1906 LDS large-print edition (and the 1907 LDS vest-pocket edition) replaced the subjunctive were with the indicative was, perhaps because the subject noun was now the singular desire. Subsequent LDS editions have retained the subjunctive were, basically because the subjunctive is common in if-clauses in the Book of Mormon text (and neither the 1906 nor the 1907 edition served as copytext for any of the later LDS editions). Notice the use of the present-tense subjunctive be in Mosiah 18:10: “if this be the desires of your hearts”. The critical text will retain the past-tense subjunctive were here in Alma 17:22.
Summary: Restore the original plural desires in Alma 17:22: “if it were his desires to dwell in the land”; also maintain the subjunctive use of were in this if-clause.