I don’t recall putting a bounty on … \… and what about it, anyways? That’s a fragment. We should consider revising it.
Turns out meta SO is the only page that uses strings from our automatically extracted database for the english -> english "localization" case.
So the cause for this bug was (of course) (again) localization.
The formatting on this particular email is fine again (kudos to @KevinMontrose):