Animations can be of various kinds and for different purposes. Page transitions, icon actions animations, font restyles, etc. Technologies are also varied - JS, CSS, SVG - all with different characteristics, browser nuances and different complexity of execution. I can’t see how we can work out a system-wide approach to using animations. 

Take a simple example - say, we want to animate Like icon. On click we want it to jump up and down and change color. This can be done via CSS transition or some svg within json and a supporting library. Seems doable, but let’s see how we can apply this elsewhere - what if we want to use animation with a Bell icon for Messenger alerts - make it cross once clicked and animate the crossline - this is not doable with simple css manipualtion - we need full svg sequence, which is unique and only works for this particular case. So, to accomodate both variants we need a way to upload various transitions and assign states at which they happen. Now  consider undoing or repeating an action - taking away a Like is easy - play animation backwarads. Same with Bell. What about “repost” - it’s not undoable - it can only re-done. So in some cases we have to play back, in some re-play. More inputs to add to Navigation builder? By the time we cover basic situations our configuration backend will look worse than MSword toolabar from nineties. 🥴

My point is - animations are best to be done at the final implementation stages, selectively and via custom injections - so as not to complicate the system too much.