I would argue that learning the language is the easy part even though in my experience some languages are much more difficult in practice to become effective in than others. The hard part is acquiring the expertise related to the domains where particular languages are commonly used. Knowing a language does not convey competence in the domain where they are typically used or the idioms imprinted on the use of the language by those users.
Knowing the language is necessary but not sufficient. There is an enormous amount of practice around language that is not implied by the language itself that you need to learn if you want to be effective.
Knowing the language is necessary but not sufficient. There is an enormous amount of practice around language that is not implied by the language itself that you need to learn if you want to be effective.