Is what the priest said true: that the Injeel (Gospel) was revealed in four versions (recitations) and is not distorted, while the Qur’an was revealed in seven versions (recitations) and Uthman ibn Affan burned them, which led to his death, with the Messenger having recommended not to burn them, and does this cast doubt on the preservation of the original version of the Qur’an?

This is a false fabrication and a baseless misconception. The Quran was revealed in the language of Quraish, and then it was expanded for other tribes to recite according to their own dialects as a facilitation. When differences arose among people, Uthman gathered the Companions and consulted them on unifying the people upon one harf (dialect/mode of recitation). The Companions unanimously agreed to recite according to one harf and burned all others. The Mushaf (copy of the Quran) that remained is the one that was written during the time of the Prophet and compiled during the time of Abu Bakr. What is said about the Prophet having enjoined against burning Masahif is a fabricated lie. Uthman was killed for illegitimate reasons, and the Companions and the scholars who followed them have all agreed upon Uthman's action, making it a conclusive proof.