As a foreigner who went to high school in Finland for a year, I'd say their English skills weren't that good. They probably do well in standardized tests becaus

As a foreigner who went to high school in Finland for a year, I'd say their English skills weren't that good. They probably do well in standardized tests because their education is geared towards tests and perfect grammar, not actual communication skills. My friends in high school would attempt to construct perfect sentences in their head before speaking a word, which made them poor conversationalists.