I've been learning Japanese for a couple decades now, and I've never heard a cafe called a "kissa". Always "kissaten". It feels like the author just make up their own slang for another language, and that doesn't feel good at all.
In addition, they wrote a book about visiting a bunch of cafes, and then they're going to leave that book in random other cafes that didn't get put into the book? I can't imagine I'd be very happy about that as a cafe owner. Especially since the book was written by a foreigner (gaijin), and the Japanese still aren't very cool with foreigners, in general. "No gaijin allowed" is still a fairly common sign for some businesses, as I understand it. It seems rather tone deaf.
In addition, they wrote a book about visiting a bunch of cafes, and then they're going to leave that book in random other cafes that didn't get put into the book? I can't imagine I'd be very happy about that as a cafe owner. Especially since the book was written by a foreigner (gaijin), and the Japanese still aren't very cool with foreigners, in general. "No gaijin allowed" is still a fairly common sign for some businesses, as I understand it. It seems rather tone deaf.