Obligatory: Don't learn programming languages. Learn programming problems and which languages were developed to solve these problems.
Also, you say you've reached a reasonable level of fluency with javascript and python. What does that mean? Having a grip on the syntax is different than being comfortable with half a dozen libraries and building an application that solves real user problems.
If you're learning for the joy of learning that's great! But maybe then try something completely different than the C family of languages. Try Prolog or Assembly and try to make some applications!
Yes! I think this is what I'm looking for ๐ thanks for saving me a bunch of time I'll check this out :)