I am not confused at all. I never wrote "formal language", I wrote "formal specification language", which is a completely different beast. You fail.
"Formal specification language" is "formal" because it's a formal language in the same sense that any of the many dialects of "regular expressions" or even PHP itself is a formal language. Nothing more, nothing less. The fact that you keep calling C/C++ standard specifications "informal" means that you're just parrotting buzzwords without actually understanding them. When you talk about formal specification languages or any formal languages at all, the word "informal" is inapplicable because it's a completely different kind of formality (syntactic formality) than the word "informal" implies (semantic formality). The word "informal" has meaning only when you want to make a distinction between formalised natural language and non-formalised natural language.