Here the 1874 RLDS edition omitted the second instance of the modal verb would; the 1908 RLDS edition restored it. Either reading is theoretically possible. In the finite clause after “desire that”, there is normally a modal (usually should or would ), but there is one example where we have a subjunctive verb form: “I desire that this land be a land of liberty” (Mosiah 29:32), not “I desire that this land should be a land of liberty”. The critical text will follow the earliest reading here in Alma 47:12, with the repeated would: “desiring that he would come down and that he would bring his guards with him”.
Summary: Maintain in Alma 47:12 the two occurrences of the modal verb would: “desiring that he would come down and that he would bring his guards with him”.