Hence whenever they read and came to the name, they pronounced instead the word Adonai (Lord) or Elohim (God). Hence in making that first translation into Greek known as the Septuagint Version (LXX) the translators followed the Hebrew custom and translated the above substitutes for God's name into their Greek version.
I now see that this statement is pure non-sense. Not pronouncing the name (as assumed it was becoming a practice) has nothing to do with how the Hebrew text (as it was WRITTEN, no how it was PRONOUNCED) into Greek. A translator would read the text and translate. The translator would find a Greek equivalent for the Hebrew words and names. So, as a Greek equivalent was to be found for each name, same would be the case for the tetragrammaton. I am sure they would be able to translate.
Also, the assumption that the name of god was not pronounced, does not mean they did not know how it should be pronounced. I hardly use swear words, but I do know how to pronounce it.