Gwiazdor and Święty Mikołaj were the two Polish terms for Santa Claus we searched and again it is very striking the extent to which they correspond with formal and linguistic borders. We must admit, however, that we are fairly uninformed when it come to Polish Christmas traditions, but our understanding (i.e., what we can decipher from a Google translation of the Polish wikipedia page) is that both characters deliver presents although Święty Mikołaj seems to be the more direct derivative of Santa.
This is probably a good time to note (again) that Santa Claus is a cultural artifact from Anglo (particularly American) practice and his diffusion has a lot to do with U.S. political and cultural power (and probably not that much to do with the Holy Roman Empire).
While many countries had similar figures, the timing of arrival (St. Nicholas' Day in early December or the Epiphany in January) varied as did the image, dress and role.
All of that being said, we have no good interpretation for the spatial distribution seen in the map above. The Wikipedia article does note that Gwiazdor is associated with the "areas of Wielkopolska and Kujawy (specifically, those parts which were under Prussian rule), Kashubian and Kociewie" which seems to correspond with out maps but we'll leave it to the readers to decide. Regardless, the extent to which Polish-language references are constricted to the formal boundaries, and what appears to be two equally legitimate claims on the proper name for a Santa Claus-like figure, remain especially interesting.