She’s a deeply flawed and frequently unsuccessful character, I think Mary Sue might not mean what you think it means.

She’s also far from perfect. She isn’t the best fencer, her novels were dismissed by editors, and she can’t figure out the mystery until it’s basically shoved in her face (she accuses the wrong people multiple times). She doesn’t know how to relate to people.

I don’t get how people can call her a Mary Sue. She is talented but is far from perfect or the best at everything she tries. Honestly a really well rounded protagonist, all things considered. It is an Addams Family project after all.