Yes, Flemish is a dialect, we are supposed to speak Dutch (Belgium, The Netherlands and Suriname form a language union).
There should be some changes in the manager languages soon though! I took over as England manager and one of the first questions was: you do not speak English, will this form a problem?
Considering we study English at the age of 15 and we do not dub our movies/shows/... I'd say my English is good enough to manage a national team!
It would be great if you could make up your own profile instead of the standard profiles SI gives. I'm from Belgium and the least I should be able to speak when graduating high school is:
Dutch (my mother tongue), French (second official language, start studying at age 10 I believe), German (third official language, start studying at age 14/15, but I admit I only have a basic knowledge of this, they should start studying this much earlier) and English (at age 15/16).
Also, some students take up courses in Spanish during their high school, they should be able to include this in their profile too! Not to mention those that go to college/uni and start studying languages...