Both the Catholic and Jehovah's Witness anthropomorphisize YHWH, but in reality the word should be pronounced as YaWa - or Ya'Wa'.
In ancient sanskrit, a short "a" is the default vowel. This is not limited to sanskrit but is a universal and generic default vowel and the most common vowel sound in most languages. The "H" simply means that the short vowel "a" is forcefully aspirated.
Hence the correct pronunciation is in my view simply YaWa or mort correctly Ya'Wa'