I don't think they talked much about their pasts. I don't think Juliet talked about Rachel either...

Three years in the Dharma Iniciative and living together? It HAD to came out at some point. Idk.

I know... I thought about that. But at the same time it was their past were so traumatic that I don't think they would like to relive that

Maybe, yes. But I really can see them talking about it at some point. With the whole Ethan thing maybe Sawyer told her. Idk about Rachel, though.

I always wondered this, but I'm not sure. I picked yes because they spent three years together so maybe one day they talked about it.
Would she have already known because of his file?

Oh! Of course! I completely forgot his file :O
So consider the question "do you think Sawyer and Juliet talked about Clementine (and Rachel)?"

I think she read his file because she calls him James. So maybe she already knew anyway.