There is no actual evidence of this myth.Or it comes from the teachings of the apostles and an understanding of the New Testament.
Where is the verifiable evidence of this claim? The example you provided previously is of an unknown chronological order, in other words, there is no verifiable evidence of which came first.The New Testament quotes of the Old Testament show a strong preference for the LXX over the modern Hebrew text even when the LXX is much different from the Hebrew. In some cases the verses only appear in the LXX.
The Greek speakers forming a Greek speaking portion of the church is tautological, and to think of them forming anything more than that is illogical, myopic, and false.The Bereans and other Greek-speaking synagogues formed the basis of the early Church when they converted to Christianity. Their scriptures are the basis for the Old Testament found in the earliest surviving Christian bibles.
For the sake of argument, even if a person considers the Greek speakers to form something more then their confusion over the extent of the canon and and the varying use of different books demonstrates that they are unreliable guides in this regard.