What is the ruling on an individual praying at home if congregational prayer in the mosque involves many errors, such as delaying Fajr prayer, chanting blessings upon the Prophet—may God's prayers and peace be upon him and his family—after every four rak'ahs of Tarawih, and the imam saying “Allahu Akbar” twice in the last rak'ah of Tarawih?

Congregational prayer is obligatory for adult men, and the mosque is not a condition for it. Tarawih prayer can be performed with the congregation, and then you can complete as much as you wish at home. The takbir in Witr is not for recitation but for Qunut, which is the madhhab of the Hanafis. Denouncing wrongdoings is done when one is able, and there is no denunciation for matters of differing opinions. If the Imam makes a mistake in recitation, prompt him, otherwise your prayer is valid. It is not permissible to miss Jumu'ah prayer. Delaying Fajr prayer until al-Isfar (the whitening of the sky) is the madhhab of the Hanafis, and there is no sin upon you for praying with them as long as they pray before sunrise. You can advise worshipers who commit mistakes indirectly. One should not abandon prayer in the mosque for these reasons; rather, pray there to attain the full reward.