In my explanation of the Present Perfect I was reasoning logically, whatever the language. There's a clear rationale for the existence of every grammatical construction possible in any language or that construction wouldn't be. Only, different languages distribute the same concepts across the grammatical constructions differently. My idea was to show exactly what you claim Phil - the logic of your mother tongue doesn't match the logic of the language you learn. The trouble is that every learner, without exception, will learn and use the foreign language by mentally doing translation from their mother tongue until they are very, very advanced learners.That's inevitable and if there's a living person who have managed to skip that step in learning a language please introduce them to me, it will benefit my understanding of the learning process a lot. I believe that every English learner of Serbian will intuitively look for the grammatical aparatus which would enable him to say the same what, in the particular example with the present perfect, would be the meanings as I explained. They will find themselves in a situation where they will want to direct my attention to the fact that they have that letter done and they will, I believe, intuitively try to differentiate the Serbian verb in a similar manner as they do in English, but that won't work for the reasons I stated in my previous post.If you reason in Serb to understand an English verb tense, you are going down the wrong track, in my opinion, however unavoidable this may seem.
I know that the very term "grammar" along with the loads of latin-derived terminology like adjectives, adverbs, subjunctive, clause etc. sounds daunting to learners but once they manage to see beyond the terminology and understand grammar as "little useful notes on the use of the language" they're going to make use of its concepts.
David Crystal has written extensively and brilliantly on the subject of the language acquisition and I suggest you read his "A little book of language", very interesting reading. Here's a quotation from the book, which is common sense I guess:
Let’s think about what happens when we learn a word. If I say that in Japanese there’s a word bara-bara, and ask you to learn it, what’s
the first question you’ll ask me? ‘What does it mean?’ That’s a very sensible question, because there isn’t much point in trying to learn a word if you don’t know what it means...But what if you’re a baby, and you can’t ask ‘What does it mean?’ because you haven’t learned to talk yet? Now what do you do? You watch and you listen. You pay attention to what’s going on around you. There’s plenty to listen to, after all. People are talking to you all the time, except when you’re having a meal or about to fall asleep. And there’s plenty of time to listen, because actually you haven’t got much else to do. While you’re awake and not eating, all you can do is lie back and take in your new world – how it looks, how it feels, how it smells, how it sounds. And especially, how it sounds when the noises come out of another human being...