@rokaklih thanks for writing in about this. It sounds as if you’re very close to setting up the WP CLI and this is by far the recommended approach to get this done – especially for a sync process. The issue with the regular action scheduler is that it only runs when people view the site; a page view is required to trigger the workers to do anything where as the CLI version will simply RUN while you have it running, and process jobs as you would expect.
This is a known limitation for bigger stores and we would recommend using it if you have the ability to do so.
Another workaround is to just make sure you have a site uptime monitor running that will ping the site on a page that’s not being cached, so it will actually trigger these processes for you behind the scenes regardless of web traffic patterns.
Hope this helps a bit with your decision to move to the CLI 🙂