Xfb here, no one inside the company knows exactly how newsfeed works either. The infrastructure and all of the components involved in generating and rendering newsfeed at this point (and for a while) have been far too large for any single person to understand. It's generally accepted as a mystery, even to those working on components of newafeed.

I worked on a component of newsfeed for a while, and yet had no clue how the rest of the system worked despite trying. That's the level of complexity involved here.