Google has some serious problems with this sentence:
Where's the verb in this sentence? I wrote "Ĉi tien mi ree estas."
Jen is used as "Here is" or "Here are" much like voila'/voici in french.
Ĉi tie mi ree estas or Tie ĉi staras mi denove should also be accepted (but without the accusative: being somewhere doesn’t count as moving): they are correct, but the verb can be replaced by jen without trouble :-)
How about 'Rejen mi'? Italian does that (rieccomi) and I don't see why Esperanto shouldn't.
At least, I understand, and I think that most Esperantists also do; so I would totally accept it. Did you report it?
Mi reestas tie ĉi?
This is accepted now: "Jen mi reestas."