I agree with you that transliteration is hardly the big issue.
But I personally would see no problem with having God's name appear in the NT in those places where the writer is quoting from the OT where the name is there. If the name "Noah" can be spelled the same in the NT as it was in the OT, then why not deal with God's name the same way?
Here I don't agree: when you translate a text you have to translate this text, not its possible sources (especially in other languages). You can transliterate Noah from the NT because the NT first transliterated it into Greek. It is now part of the Greek text you are translating.
This is not the case with Yhwh. It is never transliterated into Greek in any NT manuscript. Quotations of the OT in the NT substitute the name Yhwh with Greek nouns like kurios (Lord) or theos (God). Whatever the reason why the NT writers did it (they couldn't read Hebrew, they used excerpts from the Greek Septuagint), the fact is they did it and the NT Greek text which is to be translated is Yhwh-free (if I dare say). What the NWT did with the NT is not "restoring" the divine name, it is sheer fraud. Perhaps the only real fraud in the NWT, but a fraud all the same.