Search notes:

SETLANG.EXE

Microsoft Office 15(?) Language Preferences
SETLANG.EXE opens the Set the Office Language Preferences dialog box:
The same dialog is also displayed in Excel (or generally Office?) using File -> Options -> Language.

See also

Some (or all?) of the settings that are configured with SETLANG.EXE seem to be stored in the registry under HKEY_CURRENT_USER\Software\Microsoft\Office\_version_\Common\LanguageResources.
About Office languages

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