Maybe synchronization doesn’t copy the country code across? (I don’t have a hybrid environment, so I cannot test).

Localization is not easy, especially in a product that’s continually changing. I worked on the original ALL-IN-1 (Office product) Basic European Version in the mid-1980s and getting everything translated and to appear in the right place at the right time was a real challenge. Given the increase in functionality, lines of code, and language coverage, I imagine that I18N (internationalization) problems crop up all the time. The good thing is that at least there’s a focus on I18N across the board now.

The other feature is the default names used for mailbox items – for example the calendar. Some of our users setup their Outlook mailbox using their local language. Running powershell MailboxFolderPermission then fails for certain users when using “calendar” – instead I need to then try “kalender”.

Another interesting localization feature is that at least one French localization produces dramatically different email replies – only the date was included instead of To, From, CC and Subject fields.