I searched the JavaScript files for phrases passed to the l(...) function and checked if they are available in the English resource files of the corresponding module or in CommonUI. I found the following missing strings:

** AdministrationUI
ACLs saved

** CommonUI
An error occured please try again.
Login failed due to unhandled error case:
AM
PM

** ContactsUI
// already translated in several languages but with wrong key:
// "Sucessfully ..." instead of "Successfully ..."
Successfully subscribed to address book

** MailerUI
// Also missing in CommonUI (see above)
An error occured please try again.
// Present in SchedulerUI and ContactsUI
Toggle item
me

** PreferencesUI
An error occurred while importing the certificate. Verify your password.
// Probably typo in Preferences.service.js - should be Calendar
Calender
Open Calendar

** SchedulerUI
// From Calendar.service.js: just add a dot at the end
// "Wrong username or password." is already translated in MainUI and CommonUI
Wrong username or password