Currently, albums, events and the upload of new images (except as single image on timeline) and probably some more post types in facebook are not mirrored in the stats. this causes a considerable deviation (10%) from factual interactions. please fix and include.
After further discussion with Martin, the creator of this idea, the current background is that the missing engagement is from posts explicitly marked to be hidden by the administrator of the Facebook Page. Currently there seems to be no malfunction and the system behaves as expected, but we are still together looking into whether our system should show engagement for hidden timeline entries as well.