Thanks for posting the link. It sort of confirms that the archives often don't even know what they have. Apparently at the time of the discovery in 2003 no one knew the film might exist at the Russian archive. Aside from the Russian actor playing Watson, the film also boasts the American Carlyle Blackwell as Holmes (as noted) as well as British silent star Alma Taylor as Mrs. Barrymore. This was Blackwell's final silent film.
Interesting to note that there was a mini-exodus of British silent actors in German films at the close of the silent era. Brits like Taylor, Ivy Duke, Mabel Poulton, and Guy Newall were all in German productions (or productions co-produced with British companies) like
A Knight in London, Ghost Train, The Wrecker, The Alley Cat. Blackwell had been working in British silents since 1922, his last American silent had been
The Restless Sex in 1920.