I really doubt that the CIA (or any other US intelligence agency) would have set up such a venue, but it's quite plausible that, once that "eccentric USIS staffer" got it up and running, some right-wing zealot and/or CIA "asset" at the embassy would have started reporting on the regular habituees.

I suppose I'd be surprised if the USIS staffer(s) who started the coffeehouse project didn't have some kind of CIA file...