Looks like it’s working mostly fine except when an element leaves DOM and gets removed it doesn’t do animations. Here is a link to my project. https://put-em-down.netlify.com/
TransitionGroup is just a wrapper around Transition or CSSTransition components (that do the timings and that you don’t have). Without those components your todo gets removed immediately together with react-reveal’s Fade.
You could remove TransitionGroup altogether and nothing will change.
Mix and matching different animation libraries is generally a bad idea.