Besides not seeing any time field in the JSON for SciFi space points, I did the following to see if this was some problem with the JSON outputer:

SciFiHelicalPRTrackProcessor deserializer;
const SciFiHelicalPRTrack * helical_track = deserializer.JsonToCpp(helical_track_json);
const SciFiSpacePointArray space_points = helical_track->get_spacepoints();

And then for each space point in space_points I called get_time() and printed the value. Each time value was exactly zero (the default value from the class constructor).