I remember being struck when the Divine Name brochure being studied with this comment:
Thus it is evident that the original pronunciation of God's name is no longer known. Nor is it really important. If it were, then God Himself would have made sure that it was preserved for us to use. The important thing is to use God's name according to its conventional pronunciation in our own language. The Divine Name, p. 7
I thought: 'if the pronunciation of God's name isn't important, why are we making such a big deal about calling God Jehovah. If someone called him Yahweh we would be saying they are wrong but that is baseless.
Additionally, if the organisation's logic in the Divine Name brochure is that if God cared about the pronunciation of the Divine name he would have preserved it, so it doesn't matter how it is pronounced, then surely the same logic should apply to the name itself, which was absent from the earliest manuscripts of the New Testament we have. By the same logic, If it ever existed in the NT, it would have been preserved if God if he thought it was important. It was not preserved however, therefore it was not important. That should naturally follow. But that is not the case, and in the 2008 Watchtower they say:
The manuscripts of the New Testament that we possess today are not the originals. The original manuscripts written by Matthew, John, Paul, and others were well used, and no doubt they quickly wore out. Hence, copies were made, and when those wore out, further copies were made. Of the thousands of copies of the New Testament in existence today, most were made at least two centuries after the originals were penned. It appears that by that time those copying the manuscripts either replaced the Tetragrammaton with Kuʹri·os or Kyʹri·os, the Greek word for “Lord,” or copied from manuscripts where this had been done.*
Knowing this, a translator must determine whether there is reasonable evidence that the Tetragrammaton did in fact appear in the original Greek manuscripts (The Watchtower August 2008)