I think it’s unfortunate that the friendship between Myne and Frieda (granddaughter of Merchant’s Guild guildmaster) didn’t pan out. I wonder what happened to her.
I suspect it was cut for the squick factor of her being, effectively, a child consort. The deeper Frieda's involvement in the story, the more it would need to bring her benefactor to the front and center. Even after the timeskip, let's be honest, none of the readers are going to like this guy because of how their relationship began.
Kazuki-san's writing style tends to acknowledge the darker aspects of her world without fetishizing them the way her industry peers do, and I suspect she wrote herself into a bit of a corner with Frieda. She was intended to educate us about Devouring and how the commoner and middle classes are trapped between powerlessness and exploitation in matters adjacent to magic. Could something have been done to "save" her? Certainly, though she was not written as someone who was particularly looking to be saved. Was it narratively worth the chapter focus considering where the story was going and who Myne would be associating with? Probably not.
This makes a good segue into...
One of my least favorite points in the entire story was when the whole Rozemyne x Ferdinand thing started to crystalize. The thought alone made me feel icky. Myne was mentally always an adult and with her induced growth her body mirrored her mental age, but to Ferdinand, she is the little girl he was the guardian of.
This was one that many people were going to be uncomfortable with no matter what, and bringing Frieda's circumstances back to the forefront would have risked entrenching the perception of unaddressed child exploitation even further. The only thing I can really offer in Ferdinand's "defense" is that he was exposed to her older identity and appearance when he explored her memories, which could have anchored him into not seeing her as a child at all. (between that and her never acting like a "normal" person at all, let alone a normal child)
Myself, I'm kind of indifferent to it. He's a compelling character and deserved a good ending, but the relationship needed a little more time on the cooker to smooth out the edges. A PoV flashback regarding how he saw and felt about her from the moment he explored her memories onward would have been beneficial, and I strongly feel that his reunion with her in the mana replenishment chamber was written with the intention of being revisited in a sidestory PoV that never manifested.