The way that the library seems to expect to work is that "Carousel" is the default export for index. I don't think this is the way this library would treat the exports from the index.
Please keep your fork around so we can reference this failing test once the plugin is moved to rollup/plugins. We'll be transferring the referenced issue to the new repo.
I'm talking from this context: https://github.com/rollup/rollup-plugin-commonjs/issues/414#issuecomment-555321255
The way that the library seems to expect to work is that "Carousel" is the default export for index. I don't think this is the way this library would treat the exports from the index.