I don’t know what was going on, but are you sure she was trying to crack them and eat them? Where was she while you were candling the eggs? Still on her nest, roaming around, or trying to settle on those eggs since you were disturbing her nest?
It’s not that unusual for a hen just laying eggs, let alone a broody, to sort of peck at eggs and move them under her. A broody also turns her eggs. I don’t know how serious that hen was about opening those eggs.
It is not normal for any hen to open an egg to eat it, broody or not. It is perfectly normal for a hen to eat an egg that is already open. That’s not an egg eater, that’s just taking advantage of free protein. It’s when they open the egg to eat it that it is a problem.