the cracks aren't uncommon, that spot is terribly unsound structurally. the most likely reason for the cracks was that you cut out the visor area before sanding the helmet, since sanding the cheeks and mandibles puts a lot of stress on that area. as for the damage in the coldcast, did you guys happen to have the helmet sitting on any hard surface while you were sanding other areas?
i'm going to agree with jinto, i think you guys should probably strip it and start over; because i feel the surface needs a lot more work. it's still very lumpy, with warts and pock marks. a jango helmet should be smooth as smooth-smooth-smooth. if you guys took pictures of your work in progress, could you post them along with descriptions of what you were doing and where you were at with the build. the more information you can provide, the better. that includes tools used, sandpaper grits, paints, etc. i've done a few jango helmets in my time, i'd be happy to give you all sorts of advice, tips, and pointers to help you make the best jango helmet you can.