I guess in a nutshell you are saying:
If the Witnesses are right about this topic, then God must be giving them their support.
Um... a broken clock is right twice a day. Remember, they mentioned 1914, a huge event happened in 1914, and for many that don't investigate further, that is enough to believe in the Witnesses. But you know better SBF. You know about 1925, 1975, 2000, the generation... etc...
Same thing with this. Maybe... just maybe... Witnesses are right in their "gut feeling" that "Jehovah" was in the original NT.
Proof would only need to be an old enough manuscript of the NT (preferably 3rd century or earlier) with "IAO" or the tetragramaton in Hebrew...
With one manuscript, that would be sufficient to turn all of this from conjecture to a distinct possibility that JW's are completely right about this topic.
But then... to justify all 237 spots, manuscripts with IAO on those spots would have to be found... and that's a tall order...
Or maybe... like almost everything the Witnesses have done, maybe they're right about "Jehovah" being originally in the NT... but every single location where they placed it is wrong...
That would totally crush your hypothesis that they being right about the name being in the NT is proof of their blessing from God. It would be proof again that a broken clock is right twice a day... and they just got lucky.