I really thought this was going to be the episode where we at least saw a guardian. Because she's solidly ground-bound, I've mentally got her living in Ponyville instead of Cloudsdale. Her family could have moved with her instead of sending her to stay with a relative or such, but... She can't be living alone and desperate for a big sister presence because there's no other adults in her life -- can she?
(Imagine you're a pegasus parent with a new filly. Your home is made of clouds. And then one day, your child hoof-scraps a hole in the floor -- or is just playing at the edge of the yard and trips. For the first several years of their lives, pegasi foals would exist in a floating deathtrap. Moving downstairs until the kids figure out what their wings are for makes more sense all the time. No wonder they have flight camps: it's 'Welcome Home, Now Don't Die' 101.)
Yep, it's a Woona Sighting. Way past about time. And we've got a little more of her portfolio: she's Dream for the local Endless, explaining part of just what she does all night. Also bringing up the question of just who's thrown a loaf of bread at her lately. Chase this too far and the parallels get disturbing fast. (Place Discord as Delirium, Cadence as Desire... no, I'm stopping here.) But it does say something positive about her improving reputation that Scootaloo didn't spot her within the nightmare and immediately decide things had just gotten a thousand times worse.
Of course, there's still some really unsettling implications to this power. 'Yes, I occasionally wind up in Pinkie Pie's dreams. And then I have to lock myself away for the rest of the week.'