I'm not familiar with this person, except for that one song. It appears she does have musical theatre training. There are quite a number of people who are gnashing their teeth about this casting. Some people get a great deal of satisfaction in "dissecting" a casting change, even before the poor girl has has a chance to perform. Since this is her Broadway debut, she'll need some time to "get her feet wet." But the producers obviously think she will be able to do justice to the role. "Cinderella" needs to do whatever it takes to improve their box office figures. Best of luck to the newest Cinderella.
"Noel [Coward] and I were in Paris once. Adjoining rooms, of course. One night, I felt mischievous, so I knocked on Noel's door, and he asked, 'Who is it?' I lowered my voice and said 'Hotel detective. Have you got a gentleman in your room?' He answered, 'Just a minute, I'll ask him.'" (Beatrice Lillie)