You might want to ask more advice on one of the guinea threads from someone who has lots more experience hatching.  I know that guinea eggs have harder shells and keets can have trouble getting out if you feed lay pellet or oyster shell because it makes the shells too hard.  Also, they need more humidity at the right time.  I always let my guineas set their own eggs, but they are only able to hatch them if the rain falls at the right time.  I believe that's why they make their nest on the ground in the moist grass.  The alternative, however, would be to overrun with guinea fowl because they are such prolific layers here!   Hope you can find answers.
Maybe here????
https://www.backyardchickens.com/t/983252/humidity-problems/10