Complex sentence: It has been since extended to anyone who uses the word "Jehovah" as the name of God, whether in worship or in Biblical transmission (writing or translation), and then later was used openly in regard to worshippers of the Deity.
Split into simpler sentences: It has been extended to anyone who uses the word "Jehovah" as the name of God, whether in worship or in Biblical transmission (writing or translation). Later the term was used openly in regard to worshippers of the Deity.