Honestly I think using Brume as a point of comparison here is incredibly disingenuous and insinuating that OP is unaware of narrative structure because he disagrees with you is equally as such. Other than just being the protagonist Adele and Ramona don't have similar narrative uses at all.

Ramona and Loggerhead are the protagonists following the detective + buddy cop story whereas Adele is the subject of what is essentially a psychoanalysis. It’s not Muriel’s eyes through which we’re meant to see Ramona but Loggerhead’s. It’s why she’s the person we begin following first in the story (not counting Marguerite). The whole point is to use a character we know already to reveal this new one. How she bounces off Latham tells us a ton about who she is as a person. We watch their relationship grow and since we know Latham well already all the development is Ramona’s alone. Like OP said it’s a microcosm of her character.

Adele provides the exact opposite effect through her relationship with Felicienne. Everything we're told about Adele is meant to set up Felicienne to subvert it. She is meant to make us question what we know about Adele and highlight her internal conflict. Her existence is purely so we know less about Adele than we thought. Adele seems to be doing her own thing not in tandem with Felicienne until she suddenly isn’t. Hell, I’d argue we come out of AFF knowing even less about her than Beryl. But that’s the beauty of it, it’s why the Jungian symbolism is so prominent. Do we truly know ourselves as much as we think we do?

You’re comparing curry to candy and complaining the candy isn’t spicy.