Yes, Cold Steel, I know all of that.
They stuck in the name "Jehovah" in Revelation as well, so I maintain that Rev. 22:18 is a pertinent quote. But you could use Deut. 4:2 instead if you prefer: "YOU must not add to the word that I am commanding YOU, neither must YOU take away from it, so as to keep the commandments of Jehovah YOUR God that I am commanding YOU."
But I don't really care what the Bible has to say about it: Translators have a duty to be "faithful" to the document they are translating and not insert their own biases.
The Watchtower took it upon themselves to mistranslate the Greek word for "Lord" (Kurios) into "Jehovah" 237 times. They did this arbitrarily and inconsistently. Wherever Kurios was obviously used in reference to Jesus, they translated Kurios as "Lord".
If they had at least been consistent in their substituting "Jehovah" in place of "Kurios" then Philippians 2:9-11 would read in the NWT:
"Therefore God also has highly exalted Him and given Him the name which is above every name, that at the name of Jesus every knee should bow of those in heaven, and of those on earth and of those under the earth, and that every tongue should confess that Jesus Christ is Jehovah, to the glory of God the Father."
But that would contradict their preconceived notions about Jesus not being Jehovah, so it's painfully obvious that they let their own doctrine dictate what their Bible translation should say.
So I think this is an excellent example of one way in which they have not been faithful.
And, Yes; "discreet" and "slave" are also stupid translations. But that's what they choose to call themselves, so we have every right to call them on it and show that they have not lived up to their claim. I don't think it's just up to the JWs to decide if the GB has lived up to their claim. Since they broadcast their boast out into the world, the world has a right to judge whether or not the claim is justified.
