Is it possible that eren went back to the past? I am still confuse why Owl suddenly mentio...

We won't know until the author actually puts it into the manga and confirms it. I know there was talk how chapter 1s name is " to you, in 2000 years" suggesting time travel.

I think there is a time travel aspect and that all the titan transformer successors are linked. And because eren will to protect armin and mikasa is so strong it takes root in all the successors.

Either that or like you said eren goes back to the past. Maybe while there he talks about wanting to save mikasa.

There are a lot of different ways they can take this in my head.