I got the mortgage from Canada HSBC and we will need to open an account there. The account opening can be done in HSBC Hong Kong. The property is now rented out too. Feel free to ask questions, I am willing to share my experience.
the actual work is done by HSBC Canada, HSBC HK can only help you do the paper work to open a HSBC Canada account, after that HSBC HK can do almost nothing. (that was 2 years ago, not sure whether they have improved or not)
I am using HSBC Canada mortgage too, I got 80% mortgage loan (i.e. 20% down payment)