For me, using PDF.js in Firefox for Android, it looks even worse; most of the text is garbled junk characters (only code blocks appear correctly). It's substituting characters and using a different font which PDF.js could not load. (Another renderer is displaying it correctly.) Using character substitution as a standard technique is a really bad idea, and is the only thing that is preventing me from taking a deeper look at it with a view to using it as a backend for a play script/musical/opera libretti format that I wrote; it makes the document inaccessible to things like screen readers and prevents ready copying of text and search. Is there a good reason why substitution is used? If you're willing/compliant to the notion of removing it, I'd probably be pleased to help out with the project.
(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.)
(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.)