Generally speaking, the Castoria in Chaldea acts the exact same way as the Chaldea in lb6. Sure, she has a couple lines about not remembering you, but I mean, same old same old. In her voice lines she acts the same way, in her valentine she acts the same way,
Until.
"I'm sure that this thank you is what she- What Altria wanted to hear the most!"
Generally speaking, Castoria does not aknowledge that she's a different person, and neither does Guda. The two of them keep pretending that everything is fine and there is no ghost hanging by their shoulders. But not here. This is the one moment where Castoria breaks that unspoken rule to say "Hey, I'm not this girl you travelled with, I'm not the girl you loved so much, but I want you to know that she loved you profoundly. I know that for a fact because she is me." I am fine and normal about this. Btw.