I would recommend several solutions. From your side, QuickBooks developer team, get in touch with HangSeng Bank to make sure they recognize your software.
 From the user side (my side), I see I can import manually bank statements, but I only have PDF files from bank and there is no way to export CSV or other extensions.
Do you have a CSV file template, so I might fill it up via excel first, then save the CSV again and upload it in QuickBooks.

Alternatively, seems there is no way to use QuickBooks for Hong Kong customers using HangSeng bank and we have to switch to other software