I don't remember a hint on the movie how Jason Bourne found the home of Jarda, the only other living Treadstone assassin. Is it mentioned somewhere or are we just supposed to assume that Bourne simply used his amazing resourcefulness to find him?
I didn't notice that this was glossed over the first time I watched it, but I see two possible explanations.
At the end of The Bourne Identity, Jason Bourne briefly had access to some information about Treadstone when he infiltrates a safehouse. He could have found the information there and kept it. (This is a possible explanation, but I'm not crazy about it. If this is what the writers had in mind I think they would have alluded to it.)
Bourne was regaining some of his memories already by the end of the first film, so it's possible that if he and Jarda had ever worked closely together in the past he just knew where Jarda lived and remembered it. I think this is the more plausible explanation, and it is hinted at in the dialogue.
Jarda: Word in the ether was you'd lost your memory.
Jason Bourne: You still should have moved.
This seems to indicate that Jarda was counting on Bourne's memory loss to keep him safe. This is probably a bigger plot hole than Bourne suddenly remembering where Jarda lived. I'd think that a trained assassin would make himself disappear once all of his colleagues started turning up dead.
There is no explanation. I really cannot see the CIA allowing their Treadstone assets to know each other's addresses. I can see thing giving Bourne's Paris address to Castel and the others when they wanted him dead. But alive? I don't see it. In fact, the movie never hinted that the Treadstone assets worked together. The Professor didn't seem famliar with Bourne when they met in Southern France.
By the way, Jarda was the German asset (from Hamburg) in "THE BOURNE IDENTITY". Manheim was the German asset (from Munich) in "THE BOURNE SUPREMACY". The 2002 film never hinted there was a fifth Treadstone operative, especially since Conklin had made it clear in "IDENTITY" that he wanted all operatives in the program to go after Bourne.
It took some digging. When they meet each other at the house in Munich Jarda says "word in the ether was that you lost your memory." And Bourne replies "you still should have moved." This implies Bourne has at least some fragmented memories of prior knowledge of Jarda, or maybe that the house is covertly owned by the CIA. We know they've interacted before -- it's hard to tell, but in the flashbacks outside the hotel right before Neski's murder, it is Jarda who is the driver of the car that Conklin and Bourne are in. This is further confirmed in the screenplay.
Furthermore, there is some really interesting unused dialogue in the screenplay where Jarda says that he had eventually tracked Bourne to the motorcycle shop that Marie owns at the end of Identity to kill Bourne and Marie. Bourne reveals to Jarda that he knew Jarda had found him and so then had evaded Jarda to Goa, only even sparing Jarda's life at Marie's behest. And so it is then implied that unbeknownst to Jarda, Bourne at some point then tracked Jarda back to Jarda's Munich base, which Jarda hadn't moved from by the events in Supremacy - hence the "you still should have moved" line. "You still should have moved" and Jarda being the driver on Bourne's first mission are the only bits of all that that are actually included in the film but I think it's enough to make inferences that make sense of this little plot question.