Oh I didn't know that, that's interesting! I'm guessing there's no real evidence about how long ago that was vs. the age difference between the Lin from the orphanage and the current Lin that we know. if it matched up, maybe there isn't actually any wierd time stuff with Lin and she just aged normally.
Maybe because we've been such an annoyance to Team Meteor, she has some kind of special hell planned for us, and doesn't want us kicking the bucket before that, and/or part of that plan is making us watch the people around us suffer first.
I'm fairly sure it's been confirmed in game, though I don't remember how directly. I believe the screen in the back room of the abandoned power plant (with rotom) shows her, and I don't remember if it's in game or on the forums, but it is known that Sigmunds main reason for using shock 'therapy' is because his sister died at a young age and he believes the treatment might've saved her (who knows if it actually would've) but it wasn't allowed to be used at the time.
The 1 hour in the Citae being ~10 years outside is relatively OK, with the exception of the keys still with out time down there, however in the original post, you said the reverse of this, with 1 hour in Reborn being 10 years in the Citae (I assume you meant as how Lin got older). I also think it's possible that time is actually completely frozen down there, and the hour/morning that Adrienn mentioned is just made up of the time before xe was frozen, and the time between things being unfrozen in the present and xem meeting El/'Gardevoir'.
I don't remember a particular topic about the young Lin thing, It was just something floating around but I don't think there was a lot of evidence (an unused sprite in an old version, a bit of stuff from the online league)