Denizbaby,
Its not possible see variables values using "Send Email to self", its only for testing purpose to check email text is configured correctly.
One way around for this, You can check these email notifications in staging with the help of another user account and use the same scenario for which notification works to send emails like @mention , replies and Kudos to your posts . This will send you email notifications and you can easily see output of these variables.
Also, Be careful not to remove variables included in the plain text or HTML fields. References like these pull in data from code behind the scenes to add in variable information such as a user's name or the subject line of a post. These variables could break the email display if altered or removed.