They will eat the night crawlers whole. In fact they love them whole and living.

70 degrees is perfect for them, so your temps are good.

Just a few hints. I would consider upgrading to a 20 long or 29 gallon aquarium. 10 gallons is the absolute minimum for a single frog. Unfortunately pet shops either don't understand this or just don't care. Also a filter running 24 hours all day will help avoid issues such as disease and ammonia poisoning. But you've been doing well keeping them for 2 years.

Their eggs should be firm except for the clear jelly surrounding them. This can mean they are either old eggs or undeveloped eggs. I have heard that some frogs reabsorb their eggs but leave hard eggs blocking the way for future eggs. Unfortunately only an x-ray or sonogram can tell if that is the issue.

Try lowering the water level for a few days, then fill it again. When you fill it, place a small heater in it and raise the temp to 78 for 3 days. This should entice them to breed and empty her of eggs. Be sure to slowly lower their temp back to 72 or less after the 3 days. Throw the eggs away if you don't want to raise tads.

Other than that, I am at a loss for anything that may be causing this. I hope the little information I can offer helps.