It's not that confusing. Consider that this map is probably drawn in-universe (by an Imperial cartographer on commission from the court or some nobleman). This means that there will be differentiations, since cartography on a large scale isn't really an exact science before flying becomes a viable option. Nor is it really that important to be meticulously precise (and this map is probably not drawn to scale) when drawing a map of the entire land, since the big picture is more important than the picky details. Where are the roads? How far is it from Talabheim to Altdorf? Does it look pretty?
Consider this as well: Do you think the noblemen of Altdorf (or Middenheim, or Nuln, or wherever) want to see a map, where the Beast-infested forest stretches from horizon to horizon? This is not meant to give the ugly, naked truth. It is meant to hang from a wall, behind glass, look pretty (see the massive amounts of decoration and colouration) and inform its owners that "everything is fine, the Beast-infested forest is actually quite small".
For a comparison, see the maps produced in the past.
This would be a good example. It doesn't look that much like reality, but it gives a general idea of the shape of the world, and how the coastlines look.
I hope this has been enlightening in some way. Toodles.