I apologize for the delay, and hopefully I can straighten out when each template type gets used. Both of the use cases you have described will cause the Requestor version of the template to be delivered.
The following users receive Requestor versions of notification templates:
- Ticket Contacts
- Ticket Requestor
Users added to the Notify Other Addresses/Other Email Addresses fields will be treated as contacts for the corresponding email notification template. When some of these users have TDNext access, they will NOT receive the Ticketing User version of the template (even for requestors).
On the other hand, the following users receive Ticketing User versions of email templates:
- Ticket Reviewer
- Responsible for Ticket
- Responsible for Ticket Task
In order for these users to have an association with the ticket, they must have permission to access the ticketing application. This also requires TDNext access, and so we can assume that they are ticketing users.
Although these two templates are supposed to reflect TDNext access, the email system does not dynamically pick a template based on the user's applications. Due to this, users who request a ticket will receive the Requestor version regardless of TDNext access.
I hope this helps to explain how email templates are selected. Please let us know if you would like additional clarification or there's anything else we can do for you.