As far as Carol is aware, Cagliostro never practiced alchemy through memory combustion. The perfect body granted to her by Saint-Germain produced more than enough energy by itself to power most simple transmutations, and the lapis they eventually completed supplied the rest.

So either extremely forgetful or there's something else going on.

"Carol Malus Dienheim. You lot ran wild with the data I left behind, so I sure hope you haven't just forgotten your benefactor." She still introduced herself anyway, just to make sure. Surely there aren't two Cagliostros running around constantly trying to act that cute, right?