Smooth keyframe path

I would say your tracker needs to be more accurate. Attempt making it larger, not just the search radius, and a common trick is to export a video with a filter like contrast, and to track that instead.

As a last resort, it's also not uncommon to need to adjust it by hand for a frame here or there, but that takes a very good eye foe detail

Anything from a .smooth() expression to fiddling with the graph editor, pbviously. Impossible to say without seeing what actually the problem is. If this is the start or end of a motion, apparently the first thing to try would be to delete keyframes to minimze the micro jitter.

Mylenium