Curently, your needs could not be achieved via PowerPoint itself.
Here is a similar thread in PowerPoint UserVocie, "Voice Activated Slide Triggers", you may vote it up to let PowerPoint developers know which features are most important to you.
Besides, according to the the thread "How to use (this) speech macro in powerpoint?", the macro shown in your sharing link is WSR Macro, and you need to run WSR Macro and Speech Recognition (WSR) together. The following image shows the languages that WSR supports, you may have a look.
As I could not speek cantonese, so I could not do a test for you. Thanks for your understanding.
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