had there been any modified editions after all these challenges?
Yes, Publishers have made their own attempts at easing the controversy by way of releasing editions of the book with the word "nigger" replaced by less controversial words
Adventures of Huckleberry Finn
A 2011 edition of the book, published by NewSouth Books, employed the word "slave" (although the word is not properly applied to a freed man). 
who is clara clemens? Daughter of Samuel Clemens, who wrote as Mark Twain was she a writer like her father? She was a contralto concert singer and she managed his estate any concert where she has performed? She made her American debut as a contralto concert singer on the evening of September 22, 1906 at the Norfolk Gymnasium in Norfolk, Connecticut, assisted by violinist Marie Nichols what was her later life like? Clara played the title role in a dramatization of Twain's novel Personal Recollections of Joan of Arc at Walter Hampden's Broadway theater. apart from a writer, how else was twain referred as? He used the pen name "Thomas Jefferson Snodgrass" for a series of humorous letters what were his great works in literature? "The Adventures of Tom Sawyer", "Adventures of Huckleberry Finn", "The Great American Novel" what is the second novel about? The book is noted for its colorful description of people and places along the Mississippi River. Set in a Southern antebellum society that had ceased to exist over 20 years before the work was published who is the central character? Huckleberry "Huck" Finn what is his connection with the duke and the king in the story? Jim and Huck take two on-the-run grifters aboard the raft, who are the sons of English duke and King of France. what themes are discussed? "Adventures of Huckleberry Finn" explores themes of race and identity. what controversy did the novel create? Much of modern scholarship of "Huckleberry Finn" has focused on its treatment of race. and had these issues led the novel to be banned? Yes, upon issue of the American edition in 1885 several libraries banned it from their shelves.
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Adventures of Huckleberry Finn [SEP] Expurgated editions
Publishers have made their own attempts at easing the controversy by way of releasing editions of the book with the word "nigger" replaced by less controversial words. A 2011 edition of the book, published by NewSouth Books, employed the word "slave" (although the word is not properly applied to a freed man). Mark Twain scholar Alan Gribben said he hoped the edition would be more friendly for use in classrooms, rather than have the work banned outright from classroom reading lists due to its language. According to publisher Suzanne La Rosa, "At NewSouth, we saw the value in an edition that would help the works find new readers.