Human beings do not understand the Lord’s timetable. He hears and answers prayers but clearly does so according to his own wisdom. He did not immediately deliver the Limhites but, by “soften[ing]” the Lamanites’ hearts, the Limhites’ burdens became easier. Obviously this is Mormon’s assessment and also his style: to credit Yahweh for easing the sufferings and burdens of an oppressed people.
But such a development is also relatively normal. As time passed and the armed conflict receded into the past, immediate tensions obviously lessened. The longer the Limhites lived with their burdens, the more “normal” they became and the more easily they could live with lowered expectations of either comfort or superiority.