EASA have accepted that for smaller Part 23 aircraft of relatively low speed (we have suggested max cruising below 150kts initially), that an auto-slewed H.S.I may not be required as the pilot will have time to adjust the course pointer manually at a leg change and re-position the aircraft to the new track without going outside PRNav limits.
There is also the "alternative means of compliance" text, later in the same para 
All very much debated over the years PPL/IR have banged on the CAA about this for years, including doing flight testing with a CAA official who accepted that an EHSI is not required.