Hello NihiL.
I've spent some time walking around your map and have found a few small errors mainly to do with clip brushes, I've linked an imgur album with the pictures I've taken. Also place names don't show up in-game, you may not have packaged them correctly, they also reset when you modify the navmesh.
I hope this helps you, this map is really good, you've done a great job.
If you need anything, just ask.
-Belial

http://imgur.com/share/a/KXR77