Are you clicking on the link when it's in the Message Window in the editor?
Unfortunately the component I use for that window is buggy when it "links the links" (although a lot less buggy than it used to be after I reported many issues with the way it "links the links"). You may be running into a bug with the way it links the links in the validator message. This can also depend on the width of the Message Window and how the message is wrapped.
If this is the case then I can report it to the developer(s) if I can reproduce it. Can you send a screenshot of the way the message is displayed/wrapped in the Message Window when it doesn't properly link to the correct URL?
Unfortunately something happened to the screenshots/images that you uploaded because they are not displaying. Do you know why? Did you delete them by any chance? Otherwise there is yet another mystery that needs to be solved...
Thank you. I download the latest component update and then tried to reproduce this. I was able to reproduce it with the latest version of the component so I have reported it to the developers.
Hopefully they will fix this and then their update will eventually make it into a CSS HTML Validator update.