The Canadian authorities have modified the current tour package incentive program as of the 22nd of March 2017:
"Under proposed changes, a GST/HST rebate is no longer available to non-residents for the Canadian accommodation portion of eligible tour packages under the Foreign Convention and Tour Incentive Program if the accommodations are supplied after March 22, 2017. However, the rebate may still be available if the accommodations are supplied in 2017 and the amount owing for those accommodations is paid in full before January 1, 2018."
Accomodations sold by the conference organizer of an eligible foreign conference may still claim the taxes paid. Consult a tax specialist to find out how.