I teach French in a non-UK school. Most of my students have been learning French for 3 years, and I would say that the majority of my year 8 class could comfortably sit and pass a GCSE. The main difference are, in my opinion:
Students with an international mindset - languages are seen as very important
Many more lessons per week than you would have in a UK state school
Small classes of motivated students (with motivated parents)
Lack of tight control over how we teach
Large budget
Teacher-set assessment (no external assessment)
I focus a lot on grammar, and most of my students find my grammar lessons the most engaging. Personally I think grammar can be really fun (but I am a bit of a geek). I don't have much time for themed content - although of course I use it in class, all homework is vocabulary learning, as I feel that is something that needs to be done individually and in their preferred style. I teach them various ways of learning vocabulary and they choose what works for them. We have invested heavily in expensive vocabularly learning software, which means that even those students who might not enjoy sitting down with words to memorise really do have a vocab learning method that they enjoy.
This means, I can spend lessons focusing on delivering content, facilitating group tasks/speaking activities etc. I do not mark homework, but I spend a long time in individual consultation with students about their work. I can do this because of the increased hours and smaller classes.
I have purchased a massive range of readers, ranging from picture books to guided readers, bilingual novels and full monolingual novels. I expect each student from year 6 to read to themselves regularly in French, and I take time to hear them read, just as a primary teacher would.
Yes, I think the GCSE syllabus is set at a low level, but I think this is a reflection of the ridiculous expectations on schools nowadays. Timetabling for MFL is rarely a priority, and when you have large mixed sets for only an hour or two a week alongside a tiny budget, it is impossible to do what we really should be doing for our young linguists.
Only when languages are prioritised as a core subject will we see a return to GCSE students being able to function properly in their languages. For now, teachers are judged by the exam grades (and judged incredibly harshly). So, they have to do what they can to drag students through the GCSE. This means focusing on where they can get points, and this means learning set phrases.