The confusion is understandable as the comparison is basic and uses image hashes (https://pypi.org/project/ImageHash/), which are pretty surface level and don't always provide reliable "this image is obviously very similar to that one" results.

You are correct that when you click something in the brackets, the results returned are covers similar to what you clicked.

Still have a lot of room for improvement as I go further down this image matching rabbit hole, but the comparison's current state does provide some useful results every so often.