Hi there,
I noticed that I have duplicate inboxes when I set the language to German while using the Windows and Android versions with Sync.
The Android inbox button leads to one copy of the inbox while the Windows inbox button leads to another copy. In the root outline, two inbox folders would appear.
The problem disappeared when I switched the language back to English on both clients.
Here's the strange thing: I also use the iPad and iPhone versions, which are still in German, and they use the same inbox folder regardless of the language. Therefore, this issue only appears in the Windows/Android combination.
This issue reminds me of a similar one with IMAP email clients. They have built-in folder names like "Inbox" and "Sent." Renaming them to translated names leads to all kinds of problems. However, some email clients localize these names for display only; internally, the folder names stay in English. Finally, Windows itself has the same "problem" with its predefined Pictures and Documents folders. Internally, they always stay the same, but are displayed in the local language.
A similar issue occurs with custom views. A clean solution would be to keep the folder and view names in English internally (or map them to an ID) and only change how they are displayed when the language is changed.