The issue at this point, as I see it, is that there is additional information that is missing or yet to be uncovered/disclosed. Do you know as a matter of fact that this email template existed prior to March 25? If the email template, it’s corresponding situation (what you call a trigger) and any underlying code to make all of this function, for a password reset to be sent via BuddyPress, would have had to have been created by a plugin (that is not BuddyPress) and if true then that plugin needs to be identified in order to figure out why it has not reinstalled the email template with an associated situation (trigger). Otherwise, if the email template never existed then your problem lies elsewhere.
Normally, password resets are a function of WordPress and are sent via the wp_mail() function that is executed via the retrieve_password() function. However, I noticed that you are using the WP Mail SMTP plugin of which password resets would be sent via this plugin instead of the wp_mail() function (WordPress).