I don't think its unrealistic to me K (local) is the general knowledge of tourists check and as the PCs are either globetrotters or hobnobbing with globe trotters then they are likely to pick up stories, rumors sand legends
take for instance the writings of Marco Polo and how they affected Europe in his day. Those educated few who read his writingsa could tell you stuff about China even though they had never been there.
as another example I can tell you that in New York stands the Statue of Liberty a place called the Bronx and Central Park. It has a mayor, is in the state of NY, has yellow taxi cabs and a mixed population of italians, irish, jews, africans, etc. But I have never been to NY (and my information may be out of date)
As an ancient example I know that Alexandria in Egypt features a major library and a large jewish and Greek population (I assume people living at the time would know more)
So for a fantasy example um Ankh-Morpork is a city with a mixed population of humans, dwarfs, trolls and even undead! It sits on the River Ankh and is ruled by the Patrician. It is the seat of the Unseen University (the leading school of Wizardy on the Disc) and has an efficient Watch lead by the famous Sir Samuel Vimes.
contrast that to Gather Information Ankh Morpork - "you want anything go so old Nobby he can fix you up", "oh and don't buy any of Dibblers pies or his sausages on a stick"....