I think it looks good for a cut mane
And I agree with xlioness about cutting vertically; I cut my bangs like that so they aren't blunt cut, haha.
I never pulled/cut my Arab's mane for jumping and he has a pretty thick mane. It didn't get in the way too much, but I did used to put it in a running braid until I got used to jumping a horse without a short mane
I hope the vet clears your horse to jump, and even if not I'm glad you still have good plans for her!