Maybe in time the American School in Warsaw as well
Don't bother with them: they only accept US certified teachers.
Try the British School of Warsaw, the American International School of Warsaw, St. Paul's British School (but be careful with that one), and the European International School of Warsaw (although that might be the International European School of Warsaw).
Alternatively she could try teaching English as a foreign language. It's always hard for language schools to get teachers for the lower age groups.