Yes it's FBWF bug. We have the same problem in VistaPE. There are also ome troubles vith english characters too in vista. I have RUS and ENG versions of vista, but they have the same fbwf.sys
But i somehow doubt that this is really the fault of FBWF.
Never heared of a country specific HDD driver!
But not all too bad, I have Windows Embedded Feature Pack 2007, where exist final fbwf.sys for Embedded.
This version works perfect with native languages, but there is other problems like BSODs when shutdown.
Here it is.
Just compare the file versions and try to build and boot. May be you more lucky than I.