Accio is not supposed to work on people or creatures as per this source:
Why couldn’t Newt use ‘Accio’ to retrieve all his beasts?
‘Accio’ only works on inanimate objects. While people or creatures may be indirectly moved by ‘Accio-ing’ objects that they are wearing or holding, this carries all kinds of risks because of the likelihood of injury to the person or beast attached to an object travelling at close to the speed of light.
Yet in the new film Fantastic Beasts: The Crimes of Grindelwald Newt casts 'Accio' on a Niffler to get it back to him. He specifically says 'Accio Niffler'.
Doesn’t this break the rules set by JK?