More than 30 years ago, when we relied on snail mail, I wrote:
If any original NT writing had contained the tetragram, this would have been limited to direct quotes, not even to allusions. No original exists.
In the WT's case, they sprinkle their "Jehovah" around wherever it is needed to meet their prejudices. In assessing the WTS's "J" sources, I located their "J20", which is a listing of OT sources. This showed the places where the original -- not the NT -- contained the tetragram.
Interestingly, there are places in the NT where, if they followed their process consistently, they would have used their word "Jehovah" at inconvenient locations:
Let me be over-generous to the WTS for just a moment. The "Matthew" Gospel was written in 85 CE by expat Jews for a Jewish readership. The tetragram might have been familiar to them.
However, when we come to Paul's writings, his readers had no familiarity with the term. However, the word "Lord" (Kyrios) did have great significance, inasmuch as this was one term that was applied to the Roman Emperor. Paul used other titles that were applied to the Emperor, such as "Son of God". One can try to imagine the power of saying that Jesus was the Anointed One" (Christ) in opposition to the supposed anointing of the Emperor.
But Paul's gentile hearers had no reference to the word "YHWH".
Further, we have the evidence provided by the Nomina Sacra, which practice owed nothing to the Jews' tetragram.
On top of all that, the WTS does not ever use the tetragram, whether as ancient or square Hebrew letters, within the body of their articles in English.