"If God wanted them to call themselves "Jehovah's Witnesses," why does the NWT rendering of Acts 11:26 say that it was by divine providence that they were called "Christians"?"
That is why jehovah's witnesses are a cult in the first place. The fact that they disunited themselves from the rest of Christianity by transmuting their denomination to something resembling an anarchist proves they are not the true religion of God and not Christians. That "New Bible Study Method" (aka studying Zion's Watchtower Pubs) is plenarily unscriptural and was made to detract people from the bible but to lead them to untruth from Russell.
Genuinely appreciate this dissecting of where these particular credences emanated from and how they commenced. Clever utilization of erudition and enlightenment.