Does the prayer of the one being led become invalid if the Imam is not proficient in reciting Surat Al-Fatiha?

If the Imam commits a melodic error (laḥn) in the Fatiha that changes its meaning, then:

If he is capable of learning, his prayer is invalid, and the prayer of anyone who follows him is also invalid.

If he is unable to learn or if time is short, his prayer is valid for himself, and the prayer of those who follow him and are similarly unable (to learn) is valid. The prayer of the remaining followers is invalid.

Whoever among the congregants repeats their prayer is correct.