How does Apple Calendar sync works and what types of events can be synced?

Once you enable synchronization with Apple Calendar Tweek synchronizes tasks 1 month back from today and 12 months forward from today.

Events, all-day events, and public calendars are synchronized.

The timeframe of an event is not shown in Tweek, only the start time of that event is shown.

Note: For now, custom recurrent tasks, multiple-day events, tasks, and reminders are not supported.