There is a discrepancy in current OSM data indeed: I see "Parc Beco - Becopark" (no accent) and "Bassin Béco - Becodok" (with accent only in FR), and we also have "Avenue Émile de Beco - Émile de Becolaan" in 1050.

Current version of wikidata and wikipedia write his name with an accented E.
https://www.wikidata.org/wiki/Q4439024
https://nl.wikipedia.org/wiki/Emile_de_Béco

Of course, we can change wikidata and wikipedia but if "Beco" is the correct spelling, can you please point us to some relevant documentation.

(There are several cases where local authorities voted to name a street after someone and spelt the name wrong; this is always a difficult situation because we want our map to be correct.)