while one aspect of her character is displayed as being older, maybe..mid 30s, if you take from her back story, the back story isnt so much about what happened before MD (even though it reads as such) its a timeless extract of memory, its not something that even truly existed, much like how there was never ancient lore for MD but its still written, her back story of that part of her is also like ancient lore, its a story about what happened before, it has its points and parallels and its something that "must" have happened to explain the way that she works within the confines of MD, that back story has no bearing on who she is or any of her personalities or any of the reasons why she is like that on her deepest levels of character, which extends above MD and across game borders into real life, one aspect of her manifests as an adult, another a child, but one is younger than 23 and the other is much older in how they present themselves, saying that she's "actually 23" doesn't work as her age isn't exactly real to begin with.
MD itself is timeless, the people in it also can be if they choose, if they play a character then that character is also "frozen" in time unless that player decides to actively age them, having MD tell them how old they are is counter productive to this point and doesn't fit in with how things are, people used to tell me that "oh, youre a teenager now because you aged with being in MD 1 year" well no, because it doesnt work like that, we are spirits, we are whatever we define ourselves as and that also extends to our ages
edit: added extra and fixed typos