You can't update information on a record if you are not registered on CaraMaps or if you are not logged in to your account.
On another note, you will not be able to revise the information on a site if the latter has a designated owner. Indeed, when a user is identified as the owner, he is the only one allowed to revise and update the site.
If you think there is a mistake, you can leave a comment on the corresponding record to inform the other travelers.