Poland does allow, their orphans to be adapted.
But, there are a few main reason that no one is adopting them:
1. People generally adopt babies, adopting children is not so common and adopting young teens, is almost unheard of.
2. Actually most of these kids are not orphans, they are in children's homes because their family is dysfunctional, and weren't being taken care of, from lack of money usually.
So, people are much more willing to adopt, babies than they are a child. And most of these aren't real orphans, their families are either too poor, or don't want them.