You pretty much named the main problems. Another issue is the general concept they use. The inherit everything endless times... instead of using a component system like Unity.

There are tutorials however, and they work quite well. But the concept is to hook your game to the existing code and later remove everything else you don't need. This means you have to merge your changes with every new Neoaxis release.

I liked a lot of the engine, but this... not. at. all.
No idea what they were thinking there...