The big problem with "restoring" YHWH to the N.T texts is that those doing the "restoration" are affected by their particular Theology and Christology.
It is clear that the JW Org is against the concepts contained in the Trinity Doctrine, and so will render verses according to their beliefs, as will people in the pro Trinity camp.
We are deep in the realm of Eisegesis, not pure Translation. Of course, if one is reading an honest Translation, the reader must use Exegesis, as YHWH will not appear.
I do feel that the JW org, though restraining themselves somewhat when inserting " Jehovah" into the Text, have in fact been overly enthusiastic to do so in certain places, but again, that is only my opinion based on my understanding of the Text.
I think that all Scholarly efforts to render in a modern language what the writer intended to say are to be respected,but we have to recognize that the results are only the opinion of the Scholar.
At the end of it all we must admit two things, 1) the MSS we have are very late, have been redacted and edited and had additions included, therefore we can never know what was originally written and 2) Whether or not YHWH appeared or not, or how often it appeared, really is not very important.