Windows Insiders on the Fast Ring have now got Windows 10 build 15048. Here is a set of direct links to MUI files (x86 and x64) for that build.
Downloading MUI language packs is useful for users who need to install them on multiple PCs using ISO images of Windows 10 build 15048. They will save their Internet bandwidth and time by not downloading them again on each PC. Instead, they can save the offline package and use it for future installs. Tip: see how to install a MUI language CAB file in Windows 10.