That Romania and Iran also have strong education in STEM.

Your point is these countries don’t? What point exactly are you trying to make.

Romania is great and it's definitely punching above it's weight, just like Poland, just with the smaller population. Iran is 3 times larger than Poland in term of population so it's not an outlier like Poland and Romania.

And the point is, you should expect best results from China and US just by population alone. South Korea at 3rd place is a testament to their grueling education. But Poland and Romania (and Bulgaria) are something else. Those are not technologically advanced countries. They don't have particular stress on education.