Yes, I am Polish 100%, born and raised in Warsaw. And yes, it’s always fun to put Poles, Czechs, and Slovaks together. It raises the familiar jokes of whether a translator is needed, especially when we have foreign dignitaries visit each other’s countries.
About the comma: it was a typo, I swear!!!
The thing about “Jak sie masz?” I noticed is its more informal use between friends, people on the street, or tourists, or people here when they discover I speak Polish (and they try to as well). The older generations that I’ve known, or my family definitely does not use it as a greeting, and you’d probably get chastised in my family if the first thing you say to your parents or grandparents after a long absense is “jak sie masz?”
Well, you’re more Polish than I am. My parents were both born in southern Poland , but I was born here in–where else?–Chicago. My use pretty much corresponds to yours. I probably wouldn’t use it with my parents or grandparents either. In fact, I can’t think of using the phrase with anybody in my immediate family outside of cousins or other people my age. I would probably use the more exact jak się tata czuje “how are you (dad) feeling” or something of the like. But that does have a slightly different meaning. That said, the more familiar co tam (“what’s up” or, literally, “what’s there”) is certainly used in my family between older and younger generations.
As for the comma, I really wasn’t sure after I did the Google search. It did strike me as odd, though, and it’s good to hear that the native Pole agrees.
When I was in Warsaw, in the mid nineties, I got the impression that “Jak sie masz” was kind of universally acceptable while the twenty-somethings I hung around with used “Co slyhaç?” with each other - a habit I picked up, I guess I shouldn’ try to impress your folks with my Polish eh ?