I never had good luck allowing guinea hens to raise their own keets. They are so flock oriented, hyper, and on the go that the keets suffer in my experience. I have had far better luck allowing chicken hens to raise keets.
Grown guineas are always on the go, the keets get lost in high grass and something eats them or they die from exposure when they get wet.
Guineas are good parents they are just not in the same environment they originated from which is hot and dry,not alot of short damp grasses to get lost in.
My keets don't last 3 days when left with mom outside of a pen, so i generally gather them up as they hatch and put them in the ground brooder where mom can see them.
trying to catch those babies is a daunting task when the flock is watching them, they will gang up on me trying to protect the babies.
I have also learned that leaving keets with mom to long may result in feeding problems if not penned with keets that are already in the pen and eating, it is as if they don't know what to eat cause mom is not there to show them so i try to gather up the keets as soon as they hatch.
after the keets get their first feathers i turn them loose and some of the adults will take chare of them and show them around and do protect them.