why this is not called a motorway?
Two possible reasons:
1. It's going to be a 6-lane motorway till Abbottabad (Muslimabad / Khokhar Mera interchange), but afterwards it reduces to a 4-lane access-controlled highway, and then further degrades to 2 lanes after mansehra. So, to keep things simple they used a single code for all three types of road.
2. It was initially just a 4-lane highway, but later decided to upgrade to 6 lanes. The section till Havelian is built using asian dev bank's funding. I think they are using the E-35 code to maintain consistency with the code used in the ADB project documents.
Anyway, its operational portion is a "motorway" alright.