Did your setup ultimately prove useful in writing your book? Or did you give up part way through and that helped you get to the task of actually writing?
Python's main purpose was to enable thousands of cross-references across the books, and to transform a large, every-changing text database into a pleasing output, where different parts of the database had different output formats.
Perhaps a TeX wizard could have done it all in pure TeX, but I never could have. Besides, who wants to learn all the intricacies of TeX/LaTeX when the task in Python is so straightforward? To this day, I can't imagine a different approach.
Joining the Python and TeX pieces together into simple scripts was trivial. The Python code evolved as I got into the books, so I would recommend a rapid-iteration model of code development, rather than building a perfect edifice before starting.
in the end it was sublime (the software) and focus (not a software).
after the manuscript phase it went to google docs (one doc for each chapter) for structure and work together with the editor. then indesign for the triumvirate of me, the designer and the editor.
update: just looked at your https://github.com/poulter7/ipynb-tex, damn that looks familiar... I stand with my I) recommendation