Can you share any experiences on Steiner Waldorf secondary school in Wallonia?

Hello, We are a Brazilian family moving to Belgium from Norway in April. I am very concerned about the right school for my 12 year old son. He is a Portuguese native speaker, speaks Norwegian fluently and English very well. We intend to live in Wallonia, near Waterloo, but haven't chosen the city yet. Can anyone inform me if there are Steiner Waldorf secondary school in Wallonia? I have been writing in English to many schools but nobody answered me... Also, I learned International Schools are extremmely expensive (25-30.000 eur/year) so this is out of question for us, but Steiner schools are subsidised by the government, so do you have an idea of price?