Parachutes and GPS errors
BOI has detailed info on parachutes and how they might be improved both in use and design (handle high on shoulder is mentioned). In any case there was very little time post collision to assess a/c controllability, warn crew, jettison canopy, check parachute harness, release seat harness and evacuate.
GPS: Fitter 2: The quote was from the founder of FLARM discussing GPS reliablity. Nice trace by the way! However, why would a GPS error result in track discontinuity? Your trace could be 2km off from reality throughout the measurement period.