It seems that there isn't enough Python documentation because Doxygen is not very good at displaying Python's docstrings. The Python source code isn't very well documented either. So the source code should be commented much better before trying to generate the documentation.
Previously, Yorik mentioned that at some point they attempted to use Sphinx, but since Doxygen works better for C++, that attempt was sort of abandoned. The Sphinx files are still in the source code https://github.com/FreeCAD/FreeCAD/tree ... Doc/sphinx You may wish to inspect these files to see what can be salvaged.