I'm using DTR version 2.6.2b, but this problem has occurred since upgrading to 2.6.
This only happens for manual registrations, not front end registrations. In the email to the event admins, two of the language fields are not substituted correctly. They show up in the email message like this:
I looked and looked and have not been able to find where these tags are being used in admin.dtregister.php or elsewhere. As near as I can tell, these should be DT_TAG_EVENT_DATE and DT_PAID_AMOUNT.