I have installed LibreOffice on Windows, Linux, and OSX. The system macros where always installed under the LibreOffice Macros container in the past like this:
But when I upgraded my OSX LibreOffice to 6.35 they all were installed under My Macros instead and there was nothing under LibreOffice Macros as shown here:
In fact when I purposly create new library under LibreOffice Macros in the organizer it still shoews up under My Macros
I did try and remove any trace of the older version prior to intalling the new version including deleting LibreOffice folder from the default file path.
Interestingly OpenOffice does install on OSX with the system macros stored in the correct library container named OpenOffice Macros.