Is anything incumbent upon me if the congregants do not repeat the prayer in which I made a mistake by intentionally omitting the recitation of Al-Fatiha, and is it permissible for me to make it up on their behalf?

Firstly: There is nothing (blameworthy) upon you, because you fulfilled your duty by repeating the prayer.

Secondly: It is not permissible for you to make up (prayers) on their behalf, because prayer does not admit代理 (niyabah); there is scholarly consensus that no one prays on behalf of another, whether it be obligatory (fard), supererogatory (sunnah), or voluntary (tatwa'), nor is it permissible to make up fasting for a living person.

Thirdly: The invalidation of the Imam's prayer does not necessitate the invalidation of the congregants' prayer. This is indicated by the words of the Messenger of Allah, peace and blessings be upon him: "They lead you in prayer; if they are correct, it is for you and for them; and if they err, it is for you and against them."

Fourthly: If the prayer was silent, then your not reciting Al-Fatiha would be hidden from the congregants, and their prayer would be valid. However, if it was an audible prayer, then it was obligatory for them to inform you, and they must repeat their prayer.