If you point google to get language pack for Windows 2008 R2 server you will get multiple Microsoft links to download. But all of them eventually fail to install. The below is the proper language link.
Windows server 2008 R2 Service Pack 1 Multilingual User Interface Language Packs
The pack is available as .img file. You need to mount, use Daemon tools / magic iso Virtual CD/DVD manager (freeware)
Once mounted, you can see the contents in my computer like a CD drive.
To Install the language pack:
Control panel -> Region and language -> Keyboards and Languages -> Install \ Uninstall Languages -> click browse -> and choose the mounted img and select the language.