“La Rondine, which began as a light Viennese operetta before being transformed into an Italian tearjerker, is not a natural diva vehicle, with its wispy emotions and clunky plot…. Yet despite the work’s slightness, Ms. Opolais seemed to live within it, growing in stature as the evening went on and radiating the kind of aura—one that demands that you watch her, and sympathize with her—that defines a star.” Once again, Zachary Woolfe nails it.