"Danzig Empire" has zero hits on Google n-grams. The histories of the lands you claim were in the Danzig Empire in 1689 don't mention this empire. In 1689, Poland was in the Polish-Lithuanian Commonwealth, the Czech Republic was in the Holy Roman Empire, Hungary was in the Kingdom of Hungary, etc. See also: https://youtu.be/UY9P0QSxlnI?t=602
Also, see: https://commons.wikimedia.org/wiki/Atlas_of_European_history#/media/File:Europe_map_1648.PNG and https://commons.wikimedia.org/wiki/Atlas_of_European_history#/media/File:Western_Europe_1700.jpg