I don't know if it would help you find descendants, but there is a book that you should take a look through to see if there is a few paragraphs on Cornelius. It's an old book by Francis O'Neill, called

Irish Minstrels and Musicians: The Story of Irish Music

It was reprinted in paperback several years ago.   I can look to see if it has an index, but I don't think it does, I think you would have to just dredge through it, not that it's dull reading.