Now you will have to deal with an interactive cut-scene. Thankfully, even if you make a mistake here, you'll be able to repeat the cut-scene from the moment you've defeated the boss. Here's what you'll have to press:
1) ENTER (#1)
2) C (#2)
3) X (#3)
4) Z (#4)
Once this is done, wait for the new cut-scene to pop up on the screen.
This is going to be the final part of this mission. Your objective will be to eliminate as many cannibals as possible (#1). This is also a good spot to score a successful combo chain (#2). Also, don't forget about the possibility of picking up gold pouches. You're going to need them for another subquest.
Thankfully, you won't have to worry about falling off the raft, because it's not possible. Your character will trip a few times, but that's it. Also, you won't lose any health points as a result of these actions. Once you've dealt with several groups of cannibals, you will have to start going towards glowing dots (#1; #2). Once you've reached each of these spots, press the action key. This is also a good moment to score a combo, because unless you've pressed the key in proper areas, you won't be able to move on with course of the mission.
You should be able to reach a wooden barricade in just a few seconds. This time you're going to have to destroy three logs (#1) in order to be able to proceed with this part of the mission. As a result, the raft is going to reach a huge waterfall. A new cut-scene should appear on your screen (#2) and this mission will come to an end.
Just as before, you will be given an opportunity to take on three different side challenges. They are going to be more challenging this time, however there's nothing you should be worried about.