For offline installations, specific updates like KB4497410 contain language pack files for Windows Server 2012 R2. You can search for these directly on the Microsoft Update Catalog . Manual Installation Steps
The primary method is via the Control Panel . Navigate to Clock, Language, and Region > Add a Language . After adding your desired language, click Options and select Download and install language pack . download windows server 2012 language pack
If you have the full Multilingual User Interface (MUI) ISO, mount it to a virtual drive (e.g., Drive D:). Navigate to Clock, Language, and Region > Add a Language
Press Windows + R , type lpksetup , and hit Enter. This opens the "Install or uninstall display languages" wizard. Press Windows + R , type lpksetup , and hit Enter
Return to the Control Panel Language settings , select your new language, and click Make this the primary language .
Accept the license terms and wait for the installation to finish.
Sign out or restart the server to apply the changes across the entire system. Command Line Installation (Server Core)