Earnest the Greek Septuagint is older then the Dead Sea scrolls. I’ll look into those other inscriptions.
I believe The Tetragrammaton was substituted later to cover up and replace the gods names that were originally in the writings. Old Testament writings in my opinion were old stories gather from around the Levant and didn’t all speak of the same god. That’s why in Jerimiah for example his god never thought of a sacrifice human or animal. Other writings talk about god being from Egypt and there’s even descriptions of Egypts god Ra in one of the minor prophets. There Egyptian influences all over the place in these writings as well as Greek.