An American movie or TV show I would probably have the same level of understanding as my native language, even on references, puns, etc… English from any other nation, not to the same degree, but I’d say comparable to an american. Speaking I would say I would be quite far off. I’d say I speak a sort of “Erasmus English”, meaning I have almost exclusively had conversations with Europeans, none of which native to english. That means we borrow words which may be common to us, but not english, or accidentally apply our native grammatical rules to english.