Magic is finicky and hard to control, at best.
So what about portal magic? Possibly the only thing that is weirder than regular magic.
Why was Twi a teen, when she was very clearly in her twenties, or college age.
If the portal can... de-age, for a lack of a better term...

Could it age a certain Pony, up? And keep her well enough for four years? Let her clothing survive? Jeep her hair right?
All this and more.
Enjoy ~