I have no opinion on the website just a comment...
I have a dear friend who sings opera and has had many problems with voice coaches etc pushing her in the wrong direction and ending up with damage. Before pursuing the website I would look into making sure that the voice training she is getting is going to help her be able to sing in 10 years.
I know you are probably already being very cautious but IMO this training is WAY more important to her future career than any website. (also it may allow her to continue having fun...as opposed to getting irritable with the whole thing!
just my opinion, best wishes, lula