Here as far as I understand the fact that TeX is a Turing-complete language makes it impossible to write a converter for TeX. I read a post by Joris van der Hoeven where he said that TeX held back every other program by making it impossible to write converters. I did not find that post so I link to
https://news.ycombinator.com/item?id=27604311
where he talks about the same issue.