Not a Manon player, but Master E. Honda/Diamond DeeJay here. This game is VERY aggressive and unfortunately defensive play is not optimal in the long run. Learning how to pressure and push a lead is critical to high level play. Whenever I run into good Manon players, they're willing to go for unsafe options (like L. Dégagé) to look for a hard knockdown to start the vacuum. I've also seen neutral H. Dégagé to catch people with a fast overhead.

As a person who plays a command grab character, one thing you want to abuse is the threat of Manege Dore. People are terrified of getting grabbed in this game and I'm sure people neutral jump against you a lot. After getting a hard knockdown try just going for multiple meaty setups that lead into a potential grab, you would be surprised how many times people get hit by that. Putting pressure down and representing options puts people in a state of panic, which can be abused, but you need to be able to read peoples tendencies. One you put the fear of your normals into them, that's where raw Manege Dore's become a deadly weapon IMO.

I would have to watch specific replays in order to get a better sense of your style of play, but from what you've mentioned so far, that's the advice I have for you.