Hmmm. Trying to visualize a haflinger Arab cross. I’ve seen both have canters that weren’t optimal for jumping. Bouncy croup high on Arabs and front heavy draft horse gallumph on half lingers. Both flat canters in that the hind end isnt engaged but flat in different ways.
Not all in either breed, obviously. But this might be a horse with some challenges to doing a good jumper canter.
An ideal jumper canter is big stride, lots of jump, and the ability to extend or collect on request (alter stride length).
Maybe this mare needs more work on opening up the canter, adjusting stride within canter, collecting and extending.
If the mare is always cantering on the forehand she will be wanting to pause and push off over the jump.
.