As far as I could tell, Corona atlas support is poor. They only have index lookup. To use it with Spine, pass an "image group" as the second parameter to spine.Skeleton.new(). This makes the spine.Skeleton extend the image group instead of a "display.newGroup()". Next, in attachmentLoader:createImage(), look up the image in your "image sheet" using the attachment name. Maybe you can suffix your image names with an index so you have something meaningful in the editor and can parse out the index to lookup the region in the atlas.