civiCase emails don't use case tokens?? Print/merge does? What am I doing wrong?
When sending email via email activity only contact tokens are supported. If you have Civicase token extension installed and enabled than you can pass caseid=34 (where 34 is case id) in activity email url

eg http://example.org/civicrm/activity/email/add?atype=3&amp;action=add&amp;reset=1&amp;context=standalone&amp;caseid=34