As far as I know, The Children of Hurin comes straight out of The Silmarillion and/or Unfinished Tales; it seems to me to only have been published as a separate book in order to get more publicity from newer Tolkien fans that might not have read or thought to read The Silmarillion. So in that sense, yes I do believe it to be canonical. But like you I am not an academic, just a die-hard fan who's read them over and over again