Is it better to pray at home to avoid disagreement with an Imam who makes a clear linguistic error (laḥn jalī) in reciting Al-Fatiha, and will the one who prays (alone) attain the reward of congregational prayer and a greater reward than if he prayed behind the Imam?

If the clear grammatical error (Lahn Jali) does not change the meaning, invalidate it, or omit a letter, then the prayer is not invalidated by it. However, if the error alters or invalidates the meaning, then the prayer becomes invalid. The Malikis invalidate the prayer of one who intentionally commits a grammatical error. Praying at home is preferable if one is following someone who commits a grammatical error that invalidates the prayer, in order to attain the reward of congregational prayer, even if prayed at home.