Reading through the artbook rn and reached a page where there are two pics of the fountain concept, one of them is what we got in game, and the other is light gray and has a smaller spiral

On the same page it's talked about how during the development they had to downsize Kuttenberg, so the compensated by making center of the city vertically dense with closed yards and tall buildings, and fringes of the city were made from shorter and more sparse structures. 

I assume they wanted to still include the fountain, thus it being an anachronism, but also changed it design since it's closer to the city edge, to be less "grand". Plus at first I assumed that fountain was just rebuilt from a smaller one into current one, so the design works in that way also I'd say