I agree with lots of what you say. Just now and again you throw in a comment like "there are no Christian copies of the LXX" which throws me. And certainly there are Greek versions of the OT that are not LXX. Any book of textual criticism makes this clear.
In particular I agree we shouldn't lose sight of the big picture and the main issue of whether JWs have misrepresented the history and significance of the divine name.
I only intended to interject two main points in the discussion with my initial post:
1) I think there is something unique about the Tetragrammaton compared to the other names used of God in the Hebrew Bible. You say unique is not the right word, that it is holy. Okay then it is holy. Whichever word we use there was something special about it, I would suggest.
2) the earliest fragments of the LXX that survive and preserve parts of the text with the divine name use various forms of the divine name. None of the earliest fragments use KYRIOS. The earliest copies that use KYRIOS (or in fact the nomina sacra form KS) are from the second century CE.
You might say that, these facts notwithstanding, JWs are still wrong in various ways about the divine name. It's a discussion we could have. Personally I think there is a much stronger claim for the divine name in the original NT than many allow for. But since we can't even agree on the basic facts such as the two I made initially, and repeated above, there's not much point moving on to the wider discussion.
I respect your faith and your experience and obvious knowledge of the subject.