Since you wanted me to...not like you don't deal with me enough but for dressage since I've ridden this horse a few times lol. You do need to be tactful and I know he is not the easiest mount.
I'd like to see a more definite line set in the circles and use your OUTSIDE rein, thigh and weight to make him balance himself and not rely so much on the inside. I generally put my weight wherever I want to put the horses balance, I think of his balance taking me the direction I want to go. This is universal. The outside rein controls the inside hind leg and outside shoulder so you can create the bend around your inside leg or if you want counter flexion which helps out a lot in the canter because he needs more outside aids support (particularly leg). I think fixing that feeling along with riding more accurate lines and circles, as well as preparing in advance for transitions will help you both out a lot.
I can't help too much with the jumping but I will say your form will change a lot when you get under an eventing coach and go cross country. You get a little too forward IMO and as a former eventer, Im of the opinion of riding with a more defensive position (a little more sat back) but not behind the vertical. I feel it is more effective, especially when going cross country and you have a horse that is a little unsure or a little too game to be like hey this is the fence, we're going to it my pace, my way and re assuring the horse that your in balance and sending them for success and if they twist their back, pop their body, take off early or refuse you stay more centered over the horses back and don't lose seat as easily. And if it is a difficult combination I feel you can get your position back a lot faster and without interfering with the horse. It takes a lot of preparation to ride some of those cross country jumps effectively.