How to bake light animation

If you animated MMD light using Copy Rotation (constraints) in MMD_Light (the parent of Light), you can select Light (the child) then click Object > Animation > Bake Action....

Then in this popup, enable Clear Parents and Visual Keying. This will bake position animation coming from the parent to the baking object, then removes parent.

Now, the light should rotate on its own. but MMD Light is broken. so remove constraints from MMD_Light then parent the light back.

The result should look like this.