I have on my mind e.g.: World CHristian Peace Day in first January every each year, or: Independence Day in Poland - 11th November every each year. Reproducible: Always
Unless these are official holidays (work-off days), I doubt we can fix this; there are literally hundreds of "special days" in every country, and it would clutter the calender. If you want them in your calender, you can add them manually, and select yearly recurrence.
we do offer a very large set of holidays these days and there are google holiday calendars that you can subscribe to and probably other on-line calendars available.