I would be concerned. Get a magnaflux to see where the cracks go, and realize that the cracks may cause fast wear of the thrust surface of the main bearing. The cracks could grow and cause crank failure.
depends on the actual grade and type of material as well as any prior mishaps or wear as well as types of repairs
or subsequent surface hardening....
some surface cracks do not do anything below the surface, others can be the death of all.
some are fine if looked at every other run as in legit fuel racing when it gets torn down all the time,
being in the second picture you can clearly see it has broken thru at several points , I would change it out , no need to take a chance , and it looks like that crank has seen some heat , if its a cast crank pitch it , if its a $$$ forged unit I would send it out for a x ray to just make sure the cracks are not superficial ( only x ray or Ultrasonics can see a thru crack , Particle/dye testing will only show its a crack on the surface .) and a forged unit can be fixed by welding and grinding .