Nitpick. A jerk is an instantaneous acceleration change, not an instantaneous velocity change (that is acceleration). All the definitions are wrong in the jerk related tooltips..
@alexei, in physics you would be right. In 3d printing, you are not.
Jerk in this context should be seen as 3d printing jargon. AFAIK, in all known firmwares jerk is implemented as described in the tooltip.
Note that the unit is wrong in your fdmprinter.def.json. It should really be mm/s, not mm/s3 (even though the latter would be correct in physics)