it is just really bad wording in both the rules and the Civilopedia, specifically regarding the movement effects of Woodsman/Guerilla II.
The bottom line are the effects in the game:
Any unit with Woodsman II (Scout, Warrior, Impi, etc. . . ) can move two squares whenever the first square they enter has either Forest or Jungle. That is the only thing that matters - whether said trees are on a hill or not has no bearing on the above rule. A Warrior with Woodsman II who enters a Forested Hill with his first move will be able to move again.
Any unit with Guerilla II (Scout, Archer, etc. . . ) can move two squares whenever the first square they enter has a hill. That is the only thing that matters - whether or not said hill has Forest or Jungle has no bearing on the above rule.
Both an Archer with Guerrilla II and an Axeman with Woodsman II can move two squares, if their first one is a Wooded Hill. Weird, but true.
Impi do move 2 and they have Mobility. If their first move is into a forest or onto a hill then they will be able to move again, since Mobility reduces the cost of the terrain to 1 (but never less than 1). If they move onto a Hill with Forest or Jungle they will stop, since the cost of the terrain is 3 minus 1, or 2.
An Impi with Woodmsan II can enter a Wooded Hill first and then move again, because Woodsman trumps Mobility - they do not stack. Before the Impi, this was moot since the combo could not exist. only Armor and Mounted units can get Mobility, and neither of them can take either Woodsman or Guerrilla .
This is the way it has always been - see the Explorer (move 2, ignores terrain movement cost). Even with Woodsman II it will only move 2 squares through Jungle or Forest.