These strings, displayed when shutting down/rebooting the system from the gnome menu as a normal user, aren't translated: "In order to run "shutdown" with root's priviliegies, additional information is required." "%s's password" I haven't seen these messages in this form in Helix, so I guess they are Red Hat-specific, and in that case, RH should provide means for translating them.
This text comes from usermode. It probably isn't marked. (If usermode has gettext support at all.)
*** Bug 14707 has been marked as a duplicate of this bug. ***
Usermode 1.27 and later include gettext support, but no translations yet.
Usermode now supports gettext. The message in question is now worded as "Password for %s", to avoid ambiguity and to try steering around intricacies in translations.