Her Met gala was not advertised as a stage farewell at the time, as her NYT obituary points out. As for Cio-Cio-San, I would imagine it's a combination of the role's heaviness and its length that kept Freni from doing it in a fully staged performance. She sang Liza in PIKOVAYA DAME several times, which is no walk in the park, but is a much shorter role. She also sang Aida, though not with much regularity.
