Hello Gellyware,
if the animation you purchased has only static image sprites, and no image mesh slots, you can simply mirror the images externally to face to the right and then save them under the same name in your project folder. Then you can select all individual image slots at once in your project tree and scale only the images to -1. That works. 😉
But if you have meshes in the animation that doesn't work.
Here the images- that are themselves mirrored to the right- don't fit the skeleton. But when you scale all image slots only, it fits!