Oh, one other test you could try: in a new CMD shell, set LANG to the same value as happens in localize(), and then launch inkscape (from the same shell).
C:\path\to\inkscape> set LANG=en_US
C:\path\to\inkscape> inkscape
Does that open the GUI of current trunk without crash?
Oh, one other test you could try: in a new CMD shell, set LANG to the same value as happens in localize(), and then launch inkscape (from the same shell).
C:\path\ to\inkscape> set LANG=en_US to\inkscape> inkscape
C:\path\
Does that open the GUI of current trunk without crash?