Must a person with a valid excuse repeat the prayers of years he performed before their due time unknowingly, and is he accountable for the prayers of the congregants if he was an imam during that period?

If a person with incontinence (ma'dhur) performs ablution (wudu') before the entry of the prayer time, then there are two scenarios for him: The first is that he prays before anything from his impurity (hadath) is released; in this case, his prayer is valid. The second is that he prays after the release of incontinence without repeating ablution; in this case, his prayer is invalid, and he must repeat it according to the majority of scholars. However, according to the Malikis, ablution is not invalidated if the impurity is continuous for half or more of the time, and it is permissible for the incontinent person to follow this madhhab, and he is not required to repeat the prayers. The prayer of someone who prays behind a person with incontinence is valid according to many scholars.