Am I obliged to attend congregational prayers in a mosque where I cannot hear its Adhan, and I am unable to complete Al-Fatiha due to the Imam's speed, which prevents me from achieving khushu' (devotional humility) and tranquility?

If the Imam is not tranquil in his prayer and rushes the recitation of Al-Fatiha, making it impossible for the worshiper behind him to complete it, then it is not permissible to pray behind him, because tranquility is a pillar of prayer. The worshipers should seek another Imam who is tranquil in his prayer, or go to another mosque.

Ibn Uthaymeen mentioned that an Imam who is not tranquil and does not allow the worshiper behind him to complete Al-Fatiha, it is not permissible to pray behind him at all. He must be removed if he is an employee, and the officials must dismiss him. Whoever knows the condition of this Imam, then he must go to another mosque, while emphasizing the obligation for those who are able to pray in congregation at the mosque.