Supacode is macOS only and is a terminal emulator itself. Herdr is cross-platform and is just a multiplexer. You can use it in any terminal emulator. If you want you can even run Herdr in Supacode
Because HK is highly autonomous. If say mainland China decides to observe different time zones, Asia/Shanghai and Asia/Hong Kong would diverge. Of course, that is very unlikely to happen in the foreseeable future.