CloisteredFlame
Fluent in Kajiurago
Yeah, she's definitely "standing her ground" against potential negative sentiments.
She busts through them!
I'm pleased to see her take charge and not be squeamish about her own work. Kalafina has some of her favorite songs for crying out loud. 
I don't tend to think about 'replacement' because for every single song each performance is unique and precious in their own ways!
I love that sentiment and I fully agree. Having great vocalists who are available performing a well-written song and, do it justice, is always a treat. The original is never affected or diminished by the existence of covers.
I mean, as an example, Sawano has preformed versions of some of his really popular AoT and other songs with alternate vocalists from the original multiple times.
I would personally like to hear Forestella covering some of Kajiura's music, just for the next-level harmony potential!