GodErebos

Poor goku, Thar misunderstanding really need to get cleared or we'll be finding goku in a cave chained up.

They can't, It was said that all they can see and hear are monsters that are inside him.

Honestly you are both right and wrong because it depends on which version of Diana this is. There are many versions where she is weaker or equal than the MC. Naturally there are versions which she is stronger. As for the "shock" it makes sense since she probably didn't expect him to hold such power. That doesn't mean she thinks he's stronger. From my perspective she's just surprised a "mortal" like him is this strong.