Richard FitzAlan, 11th Earl of Arundel is under 12 years old for the birth of his child Eleanor FitzAlan, of Arundel.Elizabeth de Bohun, Countess of Arundel is under 12 years old for the birth of her child Eleanor FitzAlan, of Arundel.
After looking at this, I feel they have listed his sister Eleanor as his child. If you go back to his father Richard FitzAlan and wife they have a daughter Eleanor whose birth year matches the one for the Eleanor. Does that make sense to you?
I'm not the manager, but would also like to have this corrected.