Rath’s lore “Betrayal, Betayer” should take into account all Jennerit, but it seems it only counts troops like in similar challenges of other battleborn.
As you can see on screenshots I was counted 151 Jennerit kills in game. But In command I only have 76 kills. So my guess is that ingame built-in counter does it job well counting all the Jennerit, but the command tab counter counts troops only.