
Translations are provided by .directory files, so trying to look
up a category name without the suffix will always fail.
Commit 343b3351f1
tried to fix this previously by changing the
saved keys, but that broke existing translatable folders.
Appending the .directory suffix for the lookup instead fixes the
issue without regressing non-custom folders.
https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2623