The Canadian Opera Company has announced several cast changes for its productions of “Macbeth” and “Tosca.” The company said that Sondra Radvanovsky and Olga Busuioc have withdrawn for personal and health reasons, respectively. As a result, Bulgarian soprano Alexandrina Pendatchanska and Ukrainian soprano Liudmyla Monastyrska will now share the role of Lady Macbeth. Additionally, the Irish soprano Sinéad Campbell-Wallace and American {…}