I didn't quite grasp the point you made. Are you using Titan as an example?
Did I understand correctly that animations are responsible for the zoom? I looked at the file containing the hero-arena animations (AnimSet).xdb, as well as each individual animation, such as cast, attack00, rangeattack. None of the files contain any mention of the camera/zoom.
No, the cameras are responsible for the zoom. If you look in the advanced editor for the Camera and CameraSet tables, you will find cameras corresponding to the zoom levels.
However, the algorithm by which they are activated is unclear. In the console, you can change the configuration parameter that controls the maximum number of consecutive "zooms," so the connection is likely through the executable file.