I recently started using the Photos app built into the Apple Mac OS. I cannot find a way to edit the images' metadata except for Title, Description, and/or Keyword. And it seems that I can only do so via the Info window.
I'd be willing to do so outside the Photos app such as via a command line interface or a third-party tool.
Also note this related, yet-unanswered question: Is there a way to batch-edit metadata in the Mac OS Photos app?