You will have to programmatically share the calendar created by the service account. The calendars are owned by the service account.
What you tried :
- the calendars don't show up in your account because you have no right to access them, even though you are the appengine admin.
- entering the e-mail address of the service account does not show up the calendar in the UI because the e-mail address of the service account is not the e-mail address of the calendar. One service account could create multiple calendars.
Share the calendar programmatically with your account, log the calendar unique id and then enter it in the UI.