No, you should never change the token names related to Digesto in your Marketo Program. If you do so, Digesto will not be able to insert the content or subject line (if you use the Subject line token) in your email.
These are the default token names (case-sensitive):
DigestoEmailContent (type = Rich Text/html)
DigestoEmailContentText (type = Text)
DigestoEmailSubject (type = Text)