Trace and sweep on landscape horribly inaccurate

Traces and sweep spherical on landscapes seem to be horrible inaccurate…

I am creating something similar to an snow sledge that needs to slide down a mountain but the trace and sweep results are so bad its impossible to detect when its touching and when its not.

Red traces are when the trace doesn’t hit the ground and cyan trace colours are when they hit the ground.
How can it be this horrible? There are instances when it goes down the entire mountain without a single point of contact.