Here the 1841 British edition introduced the modal verb may. It is quite possible that the typesetter did not like or did not expect the use of a subjunctive verb form in this that-clause (namely, “that they be smitten”). Elsewhere, the text typically has a modal verb in the clause that follows “suffer (someone) that” (53 times, including five with may). There are also five cases where the verb in the that-clause can be considered in the indicative. But there are two cases in the original text where the verb is clearly in the subjunctive rather than the indicative:
However, in the first example, the 1841 typesetter once more removed the subjunctive that-clause. In that instance, he replaced it with an infinitive clause, patterned after the preceding infinitive clause in this passage:
The 1841 typesetter may have not liked the use of the subjunctive in clauses following “suffer (someone) that”. Even so, he did not correct the third instance of this usage (in Helaman 15:9). His change here in Mosiah 11:24 was not transmitted into the subsequent LDS text, but the one in Alma 39:11 was. The critical text will, of course, maintain these three original cases of the subjunctive.
Summary: Maintain the subjunctive that-clause in Mosiah 11:24 (“I will suffer them that they be smitten by their enemies”).