The title is definitely misleading: "modern LaTeX" it still isn't.
(This script format tool I wrote is also written in Python, and at present I'm writing to HTML and using wkhtmltopdf to produce a PDF, but that tool is making a mess of the text kerning so that the final result isn't as much of a pleasure to read from as it should be; your tool, however, is producing what are in my eyes quite nice-looking documents---I can easily overlook minor spacing issues at this comparatively early stage.)
The table rendering got messed up when I rewrote the line spacing code. Fixing the table rendering would just require an adjustment of the table style definition.
Then please be more honest. It's not "A modern LaTeX in 6500 lines of Python" -- it's 6500 lines of Python implementing a typesetting language with vastly inferior to TeX, or even Microsoft Word. It may have a syntax more comfortable to Python or Ruby programmers. Just say what you've done.