Occasionally, there is an animation that will work just as well in reverse - current example for me is a walk cycle. Visually, it works great when we set its speed to -1, and we save a wee bit of memory that way.
If the anim is using events, however, they don’t get fired. Sample project is just the Animation Events example, if you swap the sign on the speed:
113: modelEntity.anim.assignAnimation("Walk", walkTrack, undefined, -0.62);
Probably doesn’t count as a bug - more likely a feature request, I guess. And possibly a rare use case… and easy to work around… but maybe also a simple engine change?