Is it permissible to pray behind an imam who does not recite Al-Fatiha proficiently due to extreme speed, who reads from the Mushaf during Dhuhr prayer, and who prays the Sunnah after Asr prayer, despite being aware of these mistakes and insisting upon them?

There have been previous fatwas regarding the ruling on a congregant praying behind an Imam who rushes to the extent that the congregant cannot recite Al-Fatihah, namely: 56497, 47314, and 78155. The prayer of an Imam while reading from the Mushaf is not invalidated, according to the soundest opinion. See fatwas 30907, 56188, and 65578.