There are more languages that have standards, sure, but the languages you mention, at this point, and in general, are mostly relegated to historical maintenance and maybe some very specific niches. To me personally, a “mature” language that’s not really being used isn’t the goal. And if developers truly believed standardization was valuable, you’d expect this property to give them a significant leg up against the sorts of languages like Ruby, Python, PHP, Perl, TypeScript, etc.

That being said, I do think, considering it longer, there are languages that I am missing, like SQL, and ones that have a spec, even if it’s not under an ECMA/ISO process, like Java and Go, that I was forgetting.

I still think that using this as a necessary condition for “maturity” is misguided.