For now you can go to https://www.wechall.net/en/ (or each time select the language at the top-left of the page). You can also try asking gizmore nicely if he can change it for you.
It indeed seems over the top for this option to have the 90d period and a confirmation link via e-mail. It's just a display option. The fact that it was that only became clear to me because of your post, by the way. It being part of the "personal detail" block, I figured it was non-functional and never set it. Perhaps it's better to move this one to the normal options and call it something like "Preferred Display Language" ("preferred" because it can still be overridden with the /en/ etc.). That and either remove the currently unused "Secondary Language" or add a new non-functional "Primary Language".
P.S.: And how about automatically truncating the title if it becomes too long because the site prepends a "RE: "?