Thank you very much all your reply and sharing. We're glad that the question is solved now. It may help others who have similar issue. Here's a short summary for the problem.
SCCM Language Pack installation failed with exit code 2.
Remove the double quotes to correct the syntax error. The correct command is:
DISM.exe /image:%OSDTargetSystemDrive%\ /ScratchDir:%OSDTargetSystemDrive%\windows\TEMP /Add-Package /PackagePath:Microsoft-Windows-Server-Language-Pack_x64_en-gb.cab
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