Is it permissible for an imam of a mosque in Libya to lead communal supplications (du'a) after the Tarawih, Shaf' and Witr prayers in Ramadan, knowing that he does not consider communal supplications after obligatory prayers to be established, and that Qunut in the Tarawih prayer is forbidden in his country under the pretext of avoiding disagreement?

There is no objection to congregational supplication if it is not taken as a regular habit. However, if it is taken as a regular habit and a consistent Sunnah (definition) after every Witr prayer, then it is considered an innovated bid'ah. Ibn Taymiyyah mentioned that gathering for recitation, remembrance (dhikr), and supplication is good as long as it is not taken as a consistent Sunnah or accompanied by a reprehensible act. Imam Ahmad was asked about people gathering for supplication and raising their hands, and he said: "I do not dislike it for brothers as long as they do not intentionally gather for it, unless they do it excessively."