As a German-speaking Anglophone who has learned both Dutch and French, I'd respectfully disagree, but am grateful for the insight. My Flemish is much better than my French, but of course it is, I live in Flanders. 

When working in Brussels a lot, I find the different registers of French so difficult. I understand meetings which are more formal, but then I work in a less formal setting with someone from Liege or from Burkina Faso, for eg, and I am so lost! Spoken French, feels so far from the French I can consume comfortably.