Are there any stories where a Displaced has actually returned from being displaced and if so then what happened to them?

The Questions that I'd like answered are as follows:

1. Did they keep their powers or return to a human?

2. Did they remember what happened or not?

   • If they did remember was it like a dream to them or were they aware of it all?
3. Were they able to come and go from their home universe and the MLP one or were the two universes closed off.