Can this method be extended to go down to the sentence level ?

In the example it shows how much of the reason for an answer is due to data from Wikipedia. Can it drill down to show paragraph or sentence level that influences the answer ?

Your question should be "Can it drill down to show the paragraphs or sentences that influence the answer?"

I believe that the plagiarism complaint about llm models comes from the assumption that there is a one-to-one relationship between training and answers. I think the real and delightfully messier situation is that there is a many-to-one relationship.