Her name is Tashigi. Second, there's no reason for Caesar to show up as it is. And he created the SMILES through SAD that trace back to Vegapunk's Lineage Factor research. It all comes back to him, so he'd have the most likely cure.
I'd rather call her Shitshigi
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She's useless, it fits better her character. That's why if it's not with Hiyori, I hope Oda puts Zoro with Perona instead of an useless who reminds him of his dead friend.
As for SAD Ceasar has spent time enough with SAD to the point of being the only person who knows how to manufacture SAD, if he knows how to manufacture SAD he knows how to create a reverse effect or at least a cure. PLUS, speaking from the perspective of the narrative Oda is hiding Vegapunk, Vegapunk would probably be at this point in the plot more connected to the Reverie/Kuma instead of Wano, it makes more sense for Ceasar to show up in Wano along with the Big Mom pirates than Vegapunk himself.