Will see for the penny bug.
However for Erza it should make something happen some time after if you talk to her again. Worked when I playtested and also worked for everyone else so far.
I'm not sure if you've tested the Penny bug but something interesting that I found is that the sprit changes depending on which direction you interact with her from. If you interact from the right, it's Robin, if you do it from the top, it's Levy, from the bottom is Nemona, and the left is quite simply Penny.
Something else I found is that when talking to Faust about Ezra's fifth scene, Faust will say the dialogue telling you how to unlock the scene, but then will say: "That's the end of her content for now."