vienne I’d be interested to hear more about Rutherford being behind the increased emphasis on Jehovah’s name.
As I understand it Franz was influential in the writing department from as early as 1928. Franz authored the preface to the 1950 NWT and was presumably responsible for the adoption of Jehovah in the NT and for making the argument for its originality in the NT documents.
He was into music and was presumably supportive of the restoration of music to JW meetings shortly after Rutherford died.
He wrote a large proportion of WT books in the middle of the 20th century, including in all likelihood Babylon the Great Has Fallen, Let You Name Be Sanctified, Life Everlasting in the Freedom of the Sons of God, among others. He promoted typology, political neutrality, the blood doctrine, as well as other niche interpretive obsessions.
Altogether I reckon Franz had a huge impact on the history and development of JWs. 1975 was obviously a huge mistake and whether that clouds everything else is a judgement call. A JW might argue that there were kings in Israel who did a lot of bad things but are also remembered for their good deeds and their part in the working out of God’s purpose. Even taking 1975 into account, I think a good case could be made that JWs are unlikely to be as numerous as they are in 2025 had it not been for the intellectual and organisational energy of the Franz/Knorr team in middle decades of the 20th century. And if you think JWs are in some sense being used by God then his impact was net positive.