But yet here it is, and it was integral to the entire Sequel Trilogy because thats where the FO was hiding. So its canon.
Its proven false about 5 minutes after we hear it and we know that they Jedi don't know a ton about the Sith or their practices and them having that level of cartographical information is downright unreasonable. It was a badly written line of dialogue that shouldn't be there because it causes issues like this, where you can't have Secret Planets or Systems because "The Jedi Archives hve all of it."
Or it just makes the Jedi a bunch of ***** who don't share.