Would you say that Eliza is “successful” at Mrs. Higgins’ at-home day? Why or why not?(Act 3)

I would say she was successful. In this act we witness the transformation of Liza the flower-girl into Eliza the society lady. The change caused by repackaging her in new clothing and providing her with a new accent is so complete that she goes unrecognized by people who have seen her in her former state. Even the rough content of her conversation does not reveal her class, despite the concerns of the people who know to look out for such content.