Right now I'm definitely leaning towards simply porting Nexista to python in the form of Schematronic, instead of trying to blend nexista with cocoon, as I had originally planned.
I have a hard time understanding Cocoon because it is so big, complicated, and written in java, a language which I have very little experience with.
Furthermore, the author of pycoon, Andrey, seems to have a good understanding of python and cocoon, whereas I am learning python, but have a good understanding of nexista.
Once I'm done with Schematronic, I'll be more familiar with python, and will then hopefully understand pycoon better. I should also have another look at popoon, as it is a PHP port of cocoon. I've looked at it before and unfortunately I got confused pretty quickly. Maybe this time around I'll be able to understand it better as I've learned a little bit about cocoon while exploring pycoon.