By the way, Rilliet-de-Constant, the author of "Les cent jours en Belgique et en France" was assisting in an interesting mission in Namur, to gather French deserters, instigate others to desert, and collect information about the French army and the general situation in France:
His narration of the Saxon mutiny in Liège (pp. 345-347) is a bit fabulous though, so everything else he reports from hearsay may be just rumours as well.
On p. 348, he mentions Bourmont being informed of a (planned?) secret mission with Gerard's IV army corps.
On p. 352, he notes to have seen on 14th June (!) a French general with his staff arriving in Namur, with additional horses and baggage. One of the officers he recognized:. T***, and he learned the general was Bourmont. However, 14th June seems a bit early ? Maybe the late night ? Not too late, as Blücher was still awake.
Anyway, Rilliet states after talking to the deserters, he informed Gneisenau about the concentration of the French army. Gneisenau seemingly believed it, Blücher did not. Hard to tell whether Rilliet is exaggerating here in oder to put the "insensibles" Prussians in a bad light, or telling the plain truth.
Still, he corrobates or supports several hypotheses laid downin your book.
PS. My bad memory ... checked it in "Waterloo Betrayed" and saw you are extensively quoting and translating Rilliet's memoirs.