Here are three suggestions, the last I think it the only one not mentioned so far:
1. Use the Icons at the top when possible.
2. The Tactical View.
3. Game>Options>Combat Highlights>Circle.
What this does is instead of having to click on the enemy pixel perfect, you have an imaginary cylinder around all enemies that encompass the circle added to their feet, which makes the hit box much larger and it doesn't sway.
1. The icons at the top don't correspond with the actual enemies in any way. So I'd need to go through all of them to find the one enemy among 5 identical to attack. And doesn't work with attacks, as far as I remember.
2. A workaround like 1. Instead of fixing the actual problem they added this. Not good. I don't want to constantly switch the camera around.
3. Doesn't do that for me. The hit box seems pretty much unchanged. I just did the Valeanna fight and was chasing around the earth elementals with my mouse like always before.
I am also unable to target enemies in bushes with normal attacks, click on chests if I have some geometry too close to the camera and so on, so in my opinion there's definitely something screwed with the hit boxes in general.