Bug report: string appears untranslated

Just reporting a bug I found. This string appears untranslated in the French interface (1), even though a translation for it exists (2).

(1)

(2)

The bug also appears if I switch the interface to another language (3). On the other hand, the bug doesn't appear when I haven't indicated the guide as completed (4). So at first glance, the bug looks specific to the exact string I showed, and occurring across all translated interfaces.

(3)

(4)

I hope that's enough info to reproduce the bug. Let me know more info is needed. :)