Well, looking at what the jester represents and the confidant we have for reference, she doesnt seem to fit that.
"In the case of the Jester, the querent is misguided and unwilling to work with others, in contrast to the Fool, who is compatible with everyone. Ultimately, the Jester acts like a fool instead of genuinely being a fool. "
It doesnt seem to me that she acts like a fool at all. She seems true to herself and may have more of a duality than a front. Adachi was a funny person in the story and had a hidden side (that has quite a lot to it, which i dont have to get into for spoiler reasons, but yeah.)
Also, the game uses both jester and hunger arcana the same way, except if you go the jester route you kind of **** things up. It's just an odd arcana and I dont think a party member like her would have it. That said we still dont fully know everything (including about her), so maybe there's more to it.
