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If Image Trace doesn't work well enough for your needs then lock the layer, create a new layer, grab the pen tool and get to work. Luckily for us designers not everything is automated. If its not worth your time then you could probably purchase a vector map of Brussels or certainly contract someone to trace it for you.
I'm not sure what this map is within Brussels? Districts or something I guess? Anyways you might want to try searching for GIS / AutoCAD maps.