First of all, different people may have different opinions about what is in scope and out of scope for the site. This is quite normal, especially for interdisciplinary questions, that's why closing a question can always be countered by voting to reopen (and every user, except ♦ moderators, has only one close vote and one reopen vote per question).
I had already voted to reopen the first question; while it does require some mathematics, I don't think it will beyond comprehension for most users here. At least not the results of the answers. I've answered this question which is also at least as much about mathematics as about chess, but the Elo rating is so ubiquitous in chess (and little used outside) that I feel they belong on the site.
Now the second question is different. Most people are not using LaTeX for diagrams; the author indicates the chess part in itself is working, it's the combination of that package and another which leads to problems. Sounds like a complicated TeX issue to me (not a TeX user) which is more likely to be solved on our sister site TeX & LaTeX Stack Exchange; it might not even require chess expertise at all, just somebody who can install both packages, check some log messages or has general experience about how TeX packages can (fail to properly) interact.