Does delaying the Witr prayer congregationally until the end of the night, so that each individual may pray it with his family at home, count as a violation of the Sunnah, knowing the Hadith: "Whoever stays with the Imam until he departs, it will be recorded for him that he spent the entire night in prayer"?

There is no harm if the Imam leads the Tarawih prayer in congregation without praying Witr, so that each of them may pray Witr at the end of the night. It is hoped that by doing so, they will fall under the Hadith (definition): "If a man prays with the Imam until he departs, it will be recorded for him as if he prayed the entire night." This reward is achieved by praying behind the Imam from the beginning of his prayer until his departure, whether he prays Witr or not. This is what Sheikh Ibn Baz preferred. The opinions of scholars on this matter have varied.

As for multiple Imams leading the Tarawih prayer, there is no harm in it. They are considered as a single Imam, so whoever prays with them until they depart will attain the reward. This is what Sheikh Ibn Uthaymeen preferred.