when you say weak do you mean school standards,
things I've heard about 'international schools' in Poland (from those teaching and attending)
-the quality of education is not great (since most are learning in a foreign language) the same is true at university where programs in english are mostly... not. very. good. compared to the regular curriculum for Polish students
-parents pay and expect that their little snowflakes won't be disciplined or given failing grades.... you can imagine the rest....
-educational philosophies in Poland and English speaking countries are very different (fex whether they are teacher vs learner centered and other things as well) and international schools try to split the difference... with results that are, at best, mixed.