Wake up!
None of this is about the LXX; that is your childish dodge and it is going nowhere.
There has never been such a language as Koine. It is the result of using the equivalencies in the LXX as a rosetta stone of sorts to translate the Hebrew letters of the NT into Greek.
The Lxx was like babblefish Greek, because its translators spoke no Greek. That is why Greeks can’t read the LXX, and won’t even try.
The LXX passages in the NT are of later insertion. The original NT was totally Hebrew, but was expunged by Constantine’s armies to assist in satisfying his desire to exterminate the Jewish people.
Now go play.
“There has never been such a language as Koine.”
Really? And when I took Koine Greek at the University of California what exactly was I studying?
Koine Greek is the common Greek of antiquity that was spread across the known world by Alexander the Great.
What crackpot cult is it that fosters the profound ignorance that you display here?