The /. title calls it a "Newly-Completed Bach Work." Just to be clear, the final fugue from "Art of Fugue" has been "completed" many times over the past two centuries. Musicians as eminent as Riemann, Busoni, and Tovey have proposed completions that have been published, performed, and recorded. Wikipedia has a good article.

I haven't heard Ishizaka's version, but no matter how fine it may be it cannot be what Bach would have composed had he finished the final fugue. At one time the Bach scholar Christoph Wolff suggested that Bach probably finished the piece at some level and that the manuscript was lost. There is another theory that Bach left the final fugue incomplete on purpose.

This was not a case of Bach on his deathbed racing to finish his magnum opus. He worked on "Art of Fugue" over several years, amid many other projects, but he became blind and then died before he had the chance to wrap it up. It is astonishingly great music but not for children. By design it is free of narrative, and it may be too austere and personal for a typical concert setting.