You presume to know this as fact. However, this is not the case.
What is agreed upon by all is the NT was written in Greek.
As I was pondering this last night, it occurred to me that the entire New Testament gospels were written decades AFTER the actual events took place and, as Jesus promised, the Holy Spirit would bring to their remembrance all the things He had taught them (John 14:26). The accounts of Jesus' life and teachings even included things that the writers were not present to witness, the thoughts of the people, as well as those things Jesus said in private (i.e., His discussion with the devil after His fasting in the wilderness, Jesus' pleadings to the Father, etc.). The Holy Spirit CHOSE to reveal these things to the NT writers and their recordings of such IN Greek - it was the language spoken commonly at that time and place.
This goes to prove that what Jesus taught - even if at the time was in Aramaic/Hebrew - was preserved in Greek. Of that there is really no salient dispute.