About 30 years ago I was in Brussels and asked for a beer in a bar at the Brussels Hilton in Dutch.
The barman said he didn’t understand me!
The Vlaams area of Belgium has risen economically whereas the Walloon area had sunk.
There is an ever present antipathy between the two language groups ;especially now as the Vlaams populace pay taxes which subsidise the Walloons.
Language is a primary factor in identification and rivalry.
However freedom of speech ,trumps bad taste!