C++ doesn't qualify, to my mind, because the language has had many iterations and also because, as the post's author points out, writing C++ in the early 90s was not always a pleasant experience.
Python and even Perl are good contenders, as they have both been relatively stable languages. I'm not sure Java counts - Java 10 is quite different to Java 1.0, not just in terms of language features but often paradigms too (think 5's generics and 8's lambdas).
As for C# - I've never done .NET, so I'll have to take you on your word.