Enevhar Aldarion
Hero
I don’t think any of them discovered that Obi-Wan lives on Tatooine. Reva had to kidnap Leia to draw Obi-Wan out of hiding, but she encountered him on Daiyu, not Tatooine. Reva also learned that Luke was on Tatooine but not that Obi-Wan has been living there too. And she didn’t share that info with Vader since he’d already left her for dead.
Right. They went to Tatooine to look for a Jedi and that other one just happened to be there at the same time. And Reva learned something about a boy that Owen was hiding, but unless she took the time to get the message fixed and heard the whole thing off-camera (I hate assuming anything canon happens off-camera), all she had was the broken-up part of the message that was still audible. And I am pretty sure nothing in that part said anything about "the boy" being Vader's kid, though she would have at least sensed he was Force-sensitive as she as chasing him. And since Obi-wan did show up at the end and was face to face with her when she returned with Luke, I think she is smart enough to at least assume that Obi-wan was staying on Tatooine and watching over him.