My daughter is devoted to this cat. But this is not a reciprocal relationship, and it pains me to know my daughter wanted a kitty that would sit in her lap and purr and just be a cat but now has this one. As time has gone by, there has been very little change in behavior. I doubt things are going to change.
My cat Oscar wasn't quite as feral as you describe - she was incredibly skittish and seemed helpless in the face of her own need to claw you - but she did love boxes, toys, and catnip. FWIW, getting her a 5' cat tree was a game changer for her. She could watch us all from the safety of her perch.
Anyway, your first paragraph hits home. At one point, I decided that Oscar needed a companion. I was extremely wrong. We brought in a confident young male who proceeded to terrify her. She hid under the bed, and we even found poop under the bed because she was afraid to come out. Her ear got torn in one of their skirmishes. The new cat was incredibly loving - to humans. Clingy like you wouldn't believe. The exact opposite of Oscar. The original owner, who had sworn she would take him back if things didn't work out, "surprisingly" changed her mind and refused to take him. Eric was allergic to the new cat, and when he had a scary (but ultimately no big deal) medical situation, the doctor said the cat had to go. It seemed questionable, but with everything going on, I made the hard decision that we had to give Eros up. Especially hard as we were his third home, and he was an incredibly sweet cat - but ultimately, I knew he was incredibly adoptable - and Oscar had been there first, and was completely unviable as an adoption candidate. She would never have passed their tests.
So, yes, I chose the half feral scared and scary cat over the incredibly sweet and confident cat. Because I had a responsibility to her. I never thought I'd be a person to give up a pet, but I did, after trying to find someone to take him, even including paying to board him for a week while I tried to find him a home (he was actually great with this - he would unlock his kennel and visit with the staff. Everyone loved him). But then came a holiday, and the kennel had no room for him. I gave him up in a responsible way, provided money for whoever would adopt him, and visited him at least once a week until he was adopted after about a month. But it still sits poorly with me.