CBSubs substitutions sometimes not working in CBSubs Email workflow texts

We are watching for any other occurrences of this.

It might be due to the expiration email being triggered by a user with their language already loaded and it's causing the language switching to fail.

Perhaps related? As an admin my language parameter settings are set to English for both front and back end. So I always thought it was strange that, whenever I would click on the CBSubs Mailer -> Automation Settings, the notification showing number of messages processed in queue and number of mails sent would be sometimes in Japanese and sometimes in English. I just today realized that, if I have a front end page opened in another tab of my browser, whether I am logged in to the front end or not, that the mailer automation results notification is always based on whatever language the front end tab is currently viewing. And even if I close that tab showing a front end page, the mailer automation notifications continues to show in whatever the last language was being displayed in that now closed tab. Could something like that also possibly be affecting the expiration mails in some way?

Sounds like the manual triggering of expiration emails is related. Something going wrong with the language switch. Possibly due to it bouncing back and forth between two languages too quickly causing issues with it being unable to load the language files. Lets see if the issue persists after letting CRON handle it as that's the most ideal way to handle expirations (recommend a daily wget or curl call to the CRON URL).