“Manchu” is not to be confused with fellow artist Philippe Buchet, who worked on the wonderful Wake / Sillage sci-fi series. It seems that -this- Philippe B. is an all-around sci-fi illustrator, who only occasionally works in BD.
He has a solid LBK entry here:
https://www.lambiek.net/artists/m/manchu.htm
And here’s ~100 more of his very nice paintings:
https://scifinet.net/philippe-manchu-bouchet/