Tested, seems to work as intended, no reason to suspect a bug. There are no changes to robbers or Njerpez availability in 3.70.
Robbers can be encountered similarly in any cultural area. Njerpez are most common in the east, and almost absent in the far west and far north.
In my tests travelling from Driik to Kaumo four different parties of robbers were generated in the world, outside quests.
Hanging around in Reemi and Kaumo for a week, debugging for Njerpez raider probability, three different wandering Njerpez parties were found in the world - so thats pretty constant scouts travelling. My character never met any of these robbers nor Njerpez, but they do exist just like before.
If somebody is still in serious doubt, I can quickly check out a savegame to confirm.