"That is good to know." Of course, Greta had decided that it was safe some time ago, at least for the immediate future. Besides, even if Phinea turned without warning and attacked her, she was very skilled at duelling. Thus she was far from worried.
"If someone wished for them to never be uncovered, they would not have hidden them in such a public place, would they?" Otherwise they wouldn't exist at all. The creators knew the school would see many students over the years. The castle was an intentional puzzle from Greta's perspective. She grinned at Phinea then, delighted by her last words. "So you already knew who I am."