If you don't have that right by marriage to a European or having a European passport yourself it's going to be impossible. Unless you have a MBA in another field and find a job in that field.
Aviation language = "English" that's correct, but within the company you speak Dutch or in a large part of the country French. Even on the radio a large part of Belgium speaks French and in France (where you will have to fly to a lot when working in Belgium only a few large airports use English (ATC that is)
So converting licenses isn't the problem . And there are hardly jobs going in Belgium anyway, even for pilots with 4000+ hours that do speak the language.