I use this method because I want to make those arrows follow the line to transform and move.
However, I find that it does not need keyframe and I can’t import it to UE4 by a simple way that just like import a model with animation.
You can’t simply export path deformations like that, but you have couple of options:
1 - Use Alembic with morphing option.
2 - Use regular morph targets at every couple of frames (whichever looks best)
3 - create a bone rig, have bone follow path and couple of other extended bone on the edges to create the deformations for the bends by key framing them by hand.