To be fair, that works both ways. As much as anyone can simply copy/paste a comment into a translator to see what it translates to, the same people posting a comment in a different language than the one the website and forum is written is...can also use those translator to make sure they comment in the language the website is written in. It's simple and the same either way.
That being said, it's worth noting that posting in a different language than English is NOT against the forum policies/rules as far as I'm aware, so there's that.