Ask at Toronto check-in. The outstations have far more flexibility to issue you with a transit hotel voucher than Addis does. In Cloud Nine, you will almost certainly get it without any further questions - or they may even have it proactively waiting for you. Absolute worst case scenario you may have to buy the room + meals + transport + visa package for $70 at Addis airport but even that is a good deal for the Hilton where they will probably put you up as a Biz class pax.