While Tracker2Mask is useful to create masks, KeyTweak can be used to modify them once they are created.

This script will execute the “Time-Reverse Keyframes” Keyframe Assistant found under the Animation menu. Why? So that you can assign a keyboard shortcut.

This script displays a palette with controls for removing keyframes from the selected layers.

This script allows you to ramp the opacity at the location of the specified property’s keyframes or layer’s markers. Keyframes and markers are processed in chronological order.

This script displays a palette with controls for identifying the location of keyframes on a layer by using layer markers.