What happened to the third planet in the Kepler-47 system?
Well it looks like it has finally showed up! The Institute for Astronomy in Hawaii has put up the following press release: Scientists Fill Out A Circumbinary Planetary System. Kepler-47d turns out to be the largest of the planets, with a radius 7 times that of the Earth.

The relevant paper is Orosz et al. (2019) "Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary System".