Yes for the plumbing, no for the text.
Codex helped write the converter, but the EPUB text is parsed from the Vatican HTML. The script doesn’t rewrite or summarize anything; it just repackages the source into EPUB with TOC, footnotes, metadata, and cover.
Appreciate your work, I prefer the EPUB format. Maybe including this confirmation in the repo's README could be of help for those who stumble upon it.