As soon as a C4D scene is openend (it doesn't matter if it's an editor scene or a render scene) it starts in the background the Effex scene server which handles all the Effex scenes available and executes them.

Whenever the user creates an Effex Scene object in the object manager the server creates a scene node internally. The object in Cinema 4D is only considered to be an interface.

The internal node does not know anything about this object except that it provides attributes and port information.
The same happens for any Effex object that is placed inside an Effex scene. Internally the Effex scene creates a new node for this object interface.

The framework code is only minorly dependant on the C4D API (or any changes to it).