I'm currently playing ch 10 but I just got to the lore tablets part.
I 100% believe now that the Watcher is the villain.
The lore tablet states that Light magic and Shadow magic were both used back in the old days and that there were no ill side effects (draining your life force or losing your mind) and even states that light is nothing without darkness. The tablet continues to go on to say some cataclysm caused these two forms of magic to have negative side effects, and that the imbalance continues to grow. It even warns that the chasms could swallow magic's scared creations whole.
What I'm getting from this is that the rifts are actually good. I think they are bridges trying to restore the balance between the two forms of magic. I think that closing them will cause a grifter divide between Light magic and Shadow magic, and that the Watcher wants this to happen.
This lore tablet is described as being different so I do not believe the Watcher wrote this one, since it alludes to him being evil.
I also believe that the other realm walkers who have disappeared have been purposefully trapped by the Watcher (possibly so they can not foil his evil or plans, or so he can take their life force).
It's also possible that the cataclysm could have been caused by the Watcher himself. He is after all old enough to remember the elven old gods.
