In 1784 he became Archbishop-Elector of Cologne and remained in that office until his death, meaning that he participated as Elector in the election of his brother Leopold II in 1790.
He became Archbishop-Elector of Cologne. This was in 1784. He remained in that office until his death. This was in 1784. He participated as Elector in the election of his brother Leopold II in 1790. This was what he was meaning in 1784.