A teenager is (duh) 13yo. so 13/2 = 6.5x faster. Said another way, every not-quite 2 months the kid gains the equivalent of a year.
You’re going to be buying a lot of toys and clothes that get used once before the kid outgrows them. If you hope to provide anything like the volume of interaction and stimulation and enrichment a human kid needs, there’s gonna need to be a fulltime parent per kid.
School, even private one-on-one self-paced school, is gonna have to really firehose the kid to deliver anything close to the volume of info and knowledge and intellectual habit-shaping fed to normal human kids in the very limited time available.
Everything would play out at super speed. Which sounds frenetic and stressful as hell for the parents.
And that’s setting aside any government involvement. A government whose rules and policies and whatnot simply have no slot this peg fits into.
The kid wouldn’t directly know anything other than what they experienced as they experienced it.
But real clearly their interaction with ordinary children would be utterly strange. This month you’re hanging out with almost toddlers learning about sharing toys. Next month you’re past all that, and need to be rehomed with different playmates. The next month you’re starting to read. And need new friends again.
By the time the kid is the equivalent of a human aged WAG 5, they’d have long since realized humans are incredibly slow learners and developers compared to themselves. Given they’ll recognize this while they themselves are an emotionally and intellectually immature developing mind, I call it the “Everyone is retarded but me” effect. Which will make their already weird life a lot weirder as they develop.
I took it differently. The OP said the kid matured physicall and mentally at super speed. I’m assuming “mentally” includes emotionally.
So the e.g. “terrible twos” would occur for about 9 weeks when the kid is 4 to 6 months old. And during those months looks and acts just like a typical terrible 2yo. But by the end of that two months, they’ll look and act like a 3yo freshly done being terribly two. Two months later they’ll be a typical 4yo. Etc.
Now if your interpretation is the correct one and I’m wrong, so the kid matures emotionally at normal human rate, that is a disaster. We’re raising monsters.
My bottom line:
It would suck utterly for everyone involved.
Setting aside ethics, it’d make a fascinating case study to raise this specimen sorta like the opposite of the talking chimps, feeding it information and experience like a lab animal just to see what the outcome is. For the chimps they had to be super patient and the animals made little progress per unit time. For this person it’d be the opposite; the humans, even a team of pros, would be struggling to feed info and experiences fast enough.