Mail toolbar in ....English !!!

Hello,
it was quite a common problem when the OS was released, I myself fell victim to it.
Have you updated the "Mail & Calendar" app in the Windows Store? That resolved the issue for me.

Otherwise, try this workaround. (I can't guarantee anything, honestly):
1. Open Windows PowerShell as Administrator
2. Paste the following command in the window that opens and press Enter:

Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

3. Wait patiently for it to finish and ignore any errors that may appear.
4. If needed, restart your PC.

Thank you for your response,

I went to the store for an update, but it doesn't exist, telling me that the application is installed.

I also did the little trick on Windows PowerShell, I restarted,
the problem is still there. Those damn English are still around!!

I think we may have to wait for a Windows update, maybe.

But it's not a very big problem!
--
Thank you for your attention.
Best regards