Hi mroze,
You should start your quest in the broken parts thread:
You will get a sample of parts failures over the years with some background information when the reason of the failure is not obvious.
Unicycling being cover by a handful of brands, a vast majority of the design updates (sometimes not as obvious as others) are driven by these known weak spots that only a few dedicated riders ran into.
You top list of disciplines that are bringing the most mechanical stresses: trial, muni and street.
I remember also a couple of times somebody posting a CAD screenshot to discuss mechanical simulation of a part to visualize where a part would be most vulnerable (but cannot remember the discussion enough to find it myself).