There are a lot of differents ways to measure a nightcralwer. If your frog ate it, and it did not re-emerge from the frogs mouth, representing a a health concern, don't worry about it. Worms are good for your Ceratophrys.
I suggest you keep feeding whole live foods. While others think that you may be jeapordizing health issues by doing so, some also fail to adress the importance of
of habitat health, and minimize the danger of decomposing material. Decomposing earthworms, or pieces of same, can be dangerous.
Your size estimations may have caused reasonable alarm and the well intentioned,
concerned responses which are important considerations.