I can confirm that for Croatia it's accurate to a point. At the end of the 18th and the beginning of the 19th century two separate towns had an outbreak of syphilis, and therefore the disease was named after these two places locally. From my understanding, in both cases the disease was mostly transmitted due to poor hygiene, and not much through sexual contact. In the second town, aside from the aforementioned, a bunch of kids and their families were infected because the local doctor vaccinated the kids against pox using materials from an infected child, unintentionally.

But otherwise for the most part syphilis was called Gallic disease.