What (if anything) can be learned from accurately recording tilt motion during seismic events?
The intent with this (very, very cool) device seems to simply be to improve hazard assessment and mitigation by providing higher resolution motion data.

It reminds me of tiltmeters used on volcanoes. These devices measure changes in the flank slope of a volcano in order to assess volatility and risk (how the magma chamber is developing, etc.).

This kind of technology isn't new, but it's only been available in a precious few places. The ROMY will be able to cover a wide area, but the real holy grail is to have many mobile stations that can record local movements worldwide (as they mention in the video).