Chickens are not very bright. We used to use old light bulbs and door knobs in the nest. My dad used to whittle fake eggs in his spare time.
Try the roll away nest. I scrounged and old cabinet out of the alley. I took the back off and put in a false back raised up about two inches and some nest dividers.
The eggs roll toward the door side of the cabinet and under the false back. I shimmed it to give a slight slant. This cabinet backs up to the coop, door side out. So all I have to do is open the doors and collect the eggs.
Egg eating is caused by crowding and/or nutritional problems. Cure those problems first. Chickens need to eat lots of greens. Weeds and grass are probably lacking in their diet. Don't skimp on the oyster shell. Don't over crowd them. Let them free range all over the back yard.
Rufus