Personally, I wouldn’t use quaternions for this as I find it harder to control individual axes of motion (as you saw in my project)
What about vector 3 lerp? I was told that the quaternions are the best way rotate an object with slerp so i’m giving a shot with this one. In fact in this topic: Implementing Recoil
the OP’s script worked on me to rotate the camera but A: the animation wasn’t smooth as it was supposed to be or i felt it so. I’m not %100 with that one
B: Camera goes into a loop and gets stuck on a certain angle after you fire a few shots. I couldn’t find a way to add recoil recovery. In your script you have recoil recovery but you said you aren’t totally satisfied the way it works
C: I couldn’t find a way to adjust the recoil force in that script. No matter what value i enter, the camera rotates the same amount after the first shot