What is meant by the time—optional or necessary—during which the prayer is to be repeated for the uncovering of the minor ʻawrah according to the Malikis, and is a missed qada' prayer to be repeated if the minor ʻawrah was uncovered therein unintentionally?

Prayer must always be redone if the major 'awrah (private parts) is not covered. As for the minor 'awrah, prayer for it is redone only within the prescribed time, and for the Malikis, the time extends to the time of necessity. There is no difference in redoing the prayer within the time, whether the uncovering of the minor 'awrah occurred intentionally or unintentionally.