Jacob, I just looked at your profile - gives me hope that you might be able to help with this 
There is a more complex problem I am trying to solve. This post asks a question about an approach that could help solving that problem. A more complete description of the problem, albeit with a slightly different focus is here. That got zero replies so far - I suppose because the question was to general 
You asked what I wanted with the data from the RevolvedSurface. For processing outside of Revit I need to define a point and a vector for some families and extract that data, e.g. export to csv. The RevolvedSurface contains both (origin, axis) and is a good geometrical way of defining them. I’d also like to use the RevolvedSurface forms (and probably other forms) in the families to implement the rotation rig approach here.
In addition to getting the origin and axis out of the RevolvedSurface forms, there is another critical piece of info I hope I can get out of them. The forms are hosted on some part of the geometry of the family. And some nested family is hosted to a face of the (split) RevolvedSurface forms. For a given RevolvedSurface form, the additional info I hope I can get, is the ID of its host as well as the ID of the element hosted on it. Note that in both cases I need the IDs in the scope of the model, not the family. So somehow a mapping needs to be established between these two scopes. The objective behind this is to define relationships between certain family elements (as explained in my other post) for processing their corresponding instances later on.
So, that’s just for background. I think it makes sense to focus on the specific question in this post and create new posts for other well-defined questions of the overall problem.