I think Moho could implement it in a certain way by having it be a separate panel/window similar to the switch selection or actions. It could also be a thing in the timeline with the keyframe panel. Here is a mockup I did of both scenarios:


I hope others could see how important and useful this feature could be since it could allow people to control timing super easy and it would allow traditional animators control the timing better since its similar to a timing chart in animation so people who don't like working with motion graphs can generate better and more powerful in-betweens and have more control over Moho's generation.