Air Canada: HKG to YVR/YYC/YEG/YYZ/YOW/YUL Roundtrip ~$600-700
Flights to YVR are ~$600. Google Flight link: YVR.
Flights to YYC/YEG are $~660, connecting in YVR. Google Flight link: YYC / YEG
Flights to YYZ are ~$700. Google Flight link: YYZ
Flights to YOW are ~$720, stopover in YVR. Long layover. Google Flight link: YOW
Flights to YUL are ~$730, stopover in YVR. Google Flight link: YUL
Just look on Google Flights for your dates and it will forward you after to AC for booking. Other Canadian destinations may work, but it looks like YVR is the connection city of choice for this deal. Stackable if you have coupon codes on top of this. Samples attached below. The catch is look like you need to book on the HKG Air Canada website, which charges in HKD (conversion 1 to 6 approximately).
Multiple dates available starting October 1st to March 31st. It looks like you have to be in Canada for a maximum of 2 months. Some Christmas dates available as per attached.
Just in time for what's going in that city, good luck!