The imaam was accused of reciting Qur’aan incorrectly; what is the status of past prayers?

What is the ruling on the prayers led by an imaam who has led the prayers for more than two years, both the prayers in which Qur’aan is recited silently and those in which it is recited out loud, then those who were praying behind him accused him and said that his leading the prayers was not valid? Please note that the person was appointed as imam by a local fatwa committee and that this committee also prayed behind this imaam who is accused of not being qualified. This committee is formed of imams who are appointed to issue fatwas. 
1 – What is the ruling on the prayers led by this person whose leadership of the prayers is said to be invalid because of the alleged mistakes in Qur’aan recitation? 
2 – What is the ruling on the prayers of those who prayed behind this person for more than two years, both the prayers in which Qur’aan is recited silently and those in which it is recited out loud – during which his mistakes should have been apparent – then he was accused of being unqualified? 
3 – What is the ruling on this person’s leading the prayers, and the leading of those shaykhs who prayed behind him, then they left him because they said that he was reciting incorrectly and was not qualified.