The "Harry Potter" film crew shooting in London hadn't changed much; Chris Columbus was a very diligent director and he fully respected Rowling's opinions, and even if there were any issues, he would try his best to persuade her. As a result, the plot of the first film was not much different from what Adrian knew. As a typical example, Peeves was still cut because Columbus felt it did not contribute much to the story's progression, and though Rowling was reluctant, she was eventually convinced by his patience.
As for Little Emma, there was no doubt that she was the most outstanding among all the child actors, Columbus also said she was extremely talented. Often, when the other children had to do retakes, she got it right the first time. This was to be expected; Little Emma had often hung around on Adrian's set, and with her elfish personality, it would have been strange if she hadn't reached this level of proficiency.