The URL to the hosted image in your Delivra account technically remains editor.ne16.com. When CNAMEs are in place, the image URL will be masked in an external email with the domain specified for your account, meaning that the CNAME acts as a domain alias for editor.ne16.com.
When working inside the email editor, an administrator will see the hosted image URL as editor.ne16.com. However the image URL will be rewritten when the campaign is sent to reflect the CNAME configuration.