In short: not really as the "taalstrijd", the fight for language equality, was still raging in Belgium well after the Congo became independent.

Dutch (or Flemish) didn't even have a status at all in Belgium till the 1870's when the first wave of the Flemish Movement started to grow in strength and language laws were pushed through and only gained "official" status in 1898 with the equality law.

When Belgium gained possession over the Congo Free State in 1908, Belgium itself was still largely ruled by a Francophone upper class (including Flemings that spoke French). The next breakthrough of the Flemish movement actually came during/after World War I. There was a lot of resentment among the Flemish who in cases collaborated with the Germans because the Germans promised them linguistic freedoms. Combined with this there was a lot of anger within the Flemish part of the army that fought in the war as they were mainly relegated to the lower ranks and received almost all commands in French.

In 1921 a "territorial" principle was added to the existing language laws meaning that communities were counted every 10 years to see if the majority was Dutch or French speaking. Higher education also became available in Dutch with the University of Ghent becoming bilingual in 1923 and completely Flemish in 1930 and the prestigious Louvain University also started to add Dutch classes to its curriculum in 1930 (it is to be noted that both Ghent and Louvain are Flemish cities).

By then the Congo region had been under Leopold II/Belgian control for over 40 years and changing language politics was on no ones agenda. Also: unlike most other sub-saharan colonies the Belgian Congo still did a lot of things in the local languages or in Lingala, including primary education.

The current, constitutional, language borders were only set in 1962, and thus after the independence of Congo, and the linguistic regions (Flanders/Wallonia/Brussels) only came after a state reform in 1970