The Hamlet Project

Where exactly is Reynaldo going to get this intelligence?
That’s a lot of information to get about visitors to a city.
I can see that at a bar you might find a bartender who’s seen some Danes go through there because maybe they serve good Danish beer and maybe that bartender could tell you if they tip well and who they hang out with – but how they are in Paris, with whom, where their money comes from and where they live and how much it costs, Well, that seems a lot for a casual contact to know.
Is there perhaps a tourist bureau that keeps tabs on visiting Danes? Do they have careful records filed away in their books just in case someone needs to round them up one day? Perhaps, as a bit of a spy himself, Polonius has contacts with Parisian spies who will share information for a price.