An online book called A. I. Root, the liar number four after the Wright Brothers and their mentor, Octave Chanute, released in 2017 by Bogdan Lazar, uses newspaper articles and letters to argue that these accounts weren't true.
[Letters and articles by Root prove] that Root did not, in fact, witness any powered Wright machine flying before August 29, 1910, a date well within the aviation age. Despite pretending repeatedly in Gleanings he saw Wilbur flying on September 20, 1904, this man from Medina left behind faint traces, either in his letters or articles, that show he did not and in consequence his value as a reliable witness is zero.
The book relies only on primary sources and is so well-documented that it is hard for me to believe now that Amos Root really saw that spectacular flight of September 1904 (claimed to be the first powered flight in a circuit).
Did A. I. Root witness a Wright machine flying on September 20, 1904, as he claimed?