Most likely they're back home, but...no, they probably don't notice we're missing. When we're taken from our world, time kind of...stops from that point, until we go back...even if others are brought from a later point in time, they'll never have noticed we were missing...

Mm...no, I don't think so...I heard that the Twilight of this world has been traveling Equestria...some important business that Princess Celestia asked her to take care of...The other Twilights are staying either in the commune, where a lot of those from other worlds are staying, or with friends somewhere else...

I...think there's only the Spike native to this Equestria...