The “User Posted” template is used for emailing about a new post in a topic that the user is watching. user_watching_first_post and user_watching_category_or_tag are used for emailing about new topics. I’ve tested editing those templates on my local instance and the changes do reflect in the emails that get sent:
Can you look in /admin/email/sent and see what email types are not getting the changes you’ve made to the template?
Yes, this is an excellent point. The list of email templates in /admin/customize/email_templates is hardcoded and hasn’t been updated for years so it’s missing many new emails that have been added. Here’s a PR to add all new templates:
