Somewhat similar but from military in different country (who held ATPL in that country). Received credit for some exams; had to write others. A lot depends on how your prospective carrier in HK presents your info to CAD to determine exemption level. This will also determine the type of license you initially receive (it might be a CPL until you obtain 500 hours in HK and then converted to ATPL). Best to work through them to CAD, but you might contact CAD directly if you don't have the carrier you'll be working for. I wouldn't worry about it for the application process; just be straightforward as to your background, ratings, license, and certifications. If they want you they'll work with CAD to translate your certificates into a HK one (and CAD will determine the exams--if any--you'll need to sit). If your prospective employer is unwilling to do this they're probably not worth working for (not sure which carrier you are looking at).
Might be able to save you some trouble though. If it's CX you're considering someone of your experience level would be better off just about anywhere else. Might give the threads here about CX/KA a read.