Pretty common repair. There are some 4-5 odd threads in the knuckle. If you exceed the torque spec on the bolt, you will strip out the threads every time.
Once you've repaired it, the spec I use is "Snug". Hand on the wrench should be as close to the bolt as possible so you don't have any leverage, then snug the bolt.
The bolts don't do anything but secure one side of the caliper to the knuckle and properly locate it on the assembly. They see no braking forces, those are absorbed directly by the knuckle though the brackets on the pads.
-Ron