They may have been trying to specify it, like [Lisbon], [Kraków, Poland], [Edinburgh]. They're readers may have literally not heard of Kraków before and need that. Unfortunately, the English language uses the comma for multiple purposes so you get messes like that headline.
I think they could have used a semicolon instead, as in "Lisbon; Kraków, Poland; Edinburgh are ...".
There's a village in Christmas Island, Kiribati, by that name.
I guess Kraków just isn’t there for name recognition yet? Reordering the sentence would have made the overloaded commas a lot clearer.
They did the same to Vilnius though
Apparently also not well-known enough. But by what criteria, I have no idea...