I admit that the bindings are not in good shape, unfortunatly we don't use them ourselves and so they tend to break when we make changes to the library and don't update them. You may need some C++/SWIG knowledge to get them working. That said:
mathius777 wrote:
...simplevolume.cpp became SurfaceExtractorSimpleVolumeMaterial8.cs...
I don't think this is true. SimpleVolume should become SimpleVolumeMaterial8 and SimpleVolumeDensity8, as defined in SimpleVolume.i. What you have identified is actually a surface extractor which operates on a SimpleVolumeMaterial8.
Leave surface extraction aside for a moment, and see if you can just get SimpleVolumeMaterial8 to work. I would expect getWidth() etc to be inherited from the base class but I haven't tested it.