I pretty much agree with most everything you write, but just want to add the caveat that this is all a function of relative competence or learning stage in an L

I pretty much agree with most everything you write, but just want to add the caveat that this is all a function of relative competence or learning stage in an L2 language. That is to say, some languages that may be relatively easier to partially acquire then to fully master and visa versa. A case in point, and dear to my heart at that by way of experience, is the relative difficulty for an L1 English speaking in forming simple grammatically correct sentences in German and Mandarin, respectively. Whereas there is no question that Mandarin is the harder language to master (especially if we are talking about literacy), the high degree of analyticity relative to German makes forming sentences from words rather intuitive for the English speaker (even if English isn't quite as analytical as Mandarin in it's core modules). In other words, at least from the perspective of grammar, the beginnings of Mandarin are much easier than the beginnings of German, despite typological similarity even in inflections for plurality and the like shared between English and German.