I've tested with PCBSD 9.0 released + XBMC in French.
XBMC version seems to be not the same, but "é" character appears. No problems Appears.
I have maybe a beginning of response for my problem :
i suppose the XBMC version of PCBSD 9.1 beta is compilated in unicode.
Can you confirm that?
As XBMC version of pcbsd 9.1 is ready in french, i install it!!