It's hard to believe one doesn't exist because a cat that was once feral is different from other cats.
Not all ex-ferals are the same. I have two, one that was a feral kitten and wouldn't move off the couch for first month, nor fully felt comfortable inside for at least a year. The other one I tamed from the street, she used to be owned by someone but had turned wild and didn't trust people, it took a year before she even let me pet her, and at least another year or so before she felt fully at home in a house again (the first time I put her indoors then closer the door she immediately went frantic and jumped out a broken window that was way up high).
The once feral kitten Blaze (now 16) sprays, and is afraid of strangers and loud noises, especially garbage trucks and plastic bags. He was raised behind restaurants and lived out of dumpsters. He isn't the most well adjusted cat there is by a long shot, but he will let the people he trusts manhandle him and loves attention, and meows as much as a Siamese, but with a huge vocal range.
The other one, Blacky, is the most well adjusted cat I know. She doesn't run up to strangers but likewise isn't afraid of them; she just doesn't know them so is indifferent, outside only a few people she'll let approach her. She has no irrational fears, she doesn't even run from the vacuum until it's in the same room as her. She lets the people she knows manhandle her quiet easily and sleeps curled up on me every night.
Also, there are a large number of feral cats and ex-feral cats at the cat sanctuary I volunteer at, probably more than half the cats there, out of about 700 cats. A lot of them spook easily or are only friendly to those they know, but some are crazy affectionate cats that you would
never guess had once been feral, they run up to everyone for attention. Some feral cats only take a very short time to become tame while others may never tame up at all.
I guess I'm trying to say is you shouldn't limit a cat based on its past feral history, I know it can hugely contribute to its behaviors, however some cats are just naturally born less trusting and spooky, they don't even have to be ex-ferals to exhibit a more feral behavior. The Behaviour section should be adequate for addressing all types of issues with kitties, ex-ferals or not.