There is a link on every page to tell the GCD when you think something is in error, see "let us know" at the bottom of the page you linked. You have to have an (error) account to report an error.
There are also at least 4 or 5 GCDers around here, and one of us will do something about it.
In this particular case, the easiest thing is to find a good scan of a real copy and replace the existing scan. For that you need an (indexer/cover uploader) account.