Fans of Vicomte Raoul de Chagny

I checked, and the episode is present in the de Mattos translation, although, typically, he omits the final sentence mentioning Christine's apparent fear (Il y avait, là-dessous, du tremblement et de la crainte):
https://en.wikisource.org/wiki/The_Phantom_of_the_Opera/Chapter_VII

The scene represented Margarita's garden:

"Gentle flow'rs in the dew,
   Be message from me..."

As she sang these first two lines, with her bunch of roses and lilacs in her hand, Christine, raising her head, saw the Vicomte de Chagny in his box; and, from that moment, her voice seemed less sure, less crystal-clear than usual. Something seemed to deaden and dull her singing. ...

"What a queer girl she is!" said one of Carlotta's friends in the stalls, almost aloud. "The other day she was divine; and to-night she's simply bleating. She has no experience, no training."