Previously undisclosed emails reveal that the colleague at the center of the inquiry, the countertenor Reginald Mobley, denied to festival administrators that Matthew Halls had been racially insensitive. But clear reasons for the firing remain elusive. And the attempt to deal with an ugly personnel issue sotto voce — last week, university officials agreed to pay Mr. Halls $90,000 as part of a settlement with a nondisparagement clause — has resulted in a crescendo of criticism, from the festival’s hometown, Eugene, Ore., to England.