After applying "reduce keyframes," is it possible to see and edit the remaining keyframes?

I'm working with a keyframed Bezier Mask where the keyframes come from converting a track points behavior. The mask has many vertices and some of those need adjustments. Now, every frame is a keyframe as a result of the shape track points. Is there any way to make changes to some of the points without having to do it for every frame? I was under the impression that "reduce keyframes" would leave actual keyframes so that I could do some adjustments at the remaining intervals. Maybe this isn't possible? (Wouldn't it be cool to be able to break apart the shape animation channel into its constituent parts--a bit like breaking apart clip items in a compound clip?)

Are there any recommendations for an alternative workflow in a case such as this? (I'm working with 50fps material, and the tracking works well in about two thirds of the screen.) Many thanks.