I Don't Know How To Fix Glitches :/

I'm afraid that two things you have done there are known to not be very good for a TS3 game. Existing in=game sims should never be aged up or down within CAS as it tends to break them visually. YA to Adult or back should be okay since they share the same body types/sizes, but not child to teen. The second one is that the game needs to be quit entirely to the desktop (or Origin if relevant) in between game sessions, not reloaded from the Main Menu as doing that does not always release the contents of RAM that the game was using and we can end up with data from one game session superimposed upon another and that can lead to total save corruption.

If not averse to using mods, an NRaas MasterController Reset of the sim would be worth a try as that is a much deeper kind of reset than the cheats console resetsim kind. But if that's no help I would suggest either reverting gameplay to an older save from before you aged the child up in CAS, if you have such a save available, or replacing them in the game with a newly crafted sim.

It's possible your game or the sim who couldn't age up were already corrupted.