If you generate PDF with LaTeX output and use HTML to describe tables (because you need e.g. colspan), the generated LaTeX code using tabu is corrupted.

This is due to the fact, that you need to embrace counts with more than two digits with {}. Simply adding this curly braces to the tex output perfectly works.

Does not work (original generated TeX):
\begin{longtabu} spread 0pt [c]{*17{|X[-1]}|}

Does work (manually fixed version):
\begin{longtabu} spread 0pt [c]{*{17}{|X[-1]}|}

This is especially frustrating, because you need to use HTML tables if you want to use colspan, and colspan is a good reason to require more than 9 culumns...