Magic Lens didn't work on the first two enemies in the story (the ones with the dryad near the cave entrance). But I had targeted other enemies before that, and it worked.
I don't remember which hole I fell into in the cave since I was in the dark.^^
For the survival areas in the tree, I found the technique. I don't target any enemies and I hit in front of me. I manage to hit several enemies with this method. And if one of the enemies starts to go around me on the side, I move. Without allies and without magic.
Finally, I didn't look at how many hentai grabs there were (maybe 3). If I'm not mistaken, there are currently 5 different enemies.
Oh yes, also a question : will the other 2 succubi be playable at some point ?