From what I understand is that Belgium has three official and legal languages, which also requires each legislation to be in these languages. Only to ask for Flemish (Dutch variant) and not including French and German may not be appropriate.
I understand why Manager tried to group the localisations based on languages but some countries like Belgium have more than 1 official language see List of multilingual countries and regions - Wikipedia
I would have preferred just to use a country list and where more than 1 language is needed to add these localisations. Either way the argument here is that Belgium needs more versions.