Rabbi Ari Enkin wrote a couple of articles about this explaining why pronouncing these words would not be problematic.
In the first, a book review, he writes:
There is also an especially interesting chapter on the various names of God, their meanings and their usages. In one such discussion the author vigorously argues that the word “Jehovah” cannot possibly be a translation of the “Y-H-V-H” and hence there is nothing halachically problematic with referring to the religious group “Jehovah’s Witnesses” when appropriate.
After some less than positive feedback, he wrote a longer essay explaining his position:
Rubin notes that the correct pronunciation of the Y-H-V-H- was lost during the Talmudic period. The name was used as part of the Temple Service during the First Temple period. During the Second Temple period the name was not used as it was feared that the name would be misused or articulated unlawfully. As a result of this disuse of the Y-H-V-H the correct pronunciation of The Name was lost.
He quotes from Rabbi Rubin's book:
The first [error] is the attempt to read the Y-H-V-H with the vowels that appear with it in the printed Tanach text. While the vowels are actually the vowels of the word Adon-oi, the Chataf Patach under the Alef of Adon-oi changes to a Shevah under the Yud of Y-H-V-H. The second mistake is that the English readers took the German transliteration of the mistaken reading –Jehovah- and pronounced the letter J as a J. In German the letter J is pronounced as a Y. Thus, the German really reads Yehovah. Nevertheless, whether you pronounce it as the Germans did or as the Americans do, the word Jehovah/Yehovah is total gibberish and has no sanctity whatsoever according to the halacha. Modern scholars introduced an equally erroneous pronunciation, again based on the German, of Yahweh. This word is also gibberish and has no meaning or legal standing. (The How & Why of Jewish Prayer p.531)
Following these two articles, R' Ari Enkin wrote an article offering some challenges and some suggestions as to why one may want to be strict (and say 'J's witnesses', etc.) though no conclusion either way.
In a footnote, R' Ari Enkin wrote, "even if it is indeed God’s name, the Shach (YD 179:11) seems to say that God’s name written in a foreign language has no sanctity"