I have all the MUI's for the original non-SP1. I have gotten the SP1 MUI's, but I cannot install more than 1 at a time, and even if I install only one then test it in VirtualBox and it doesn't show up. Error: String reference not set to an instance of a String. Parameter namerefix
You can use DISM /online /add-package to add new language to windows and do some googling on how to change to that language It does work.