Hmmm, I'll have to check up on that. The translations themselves are for the description/title that appears under the applet in the control panel. Once launched,(LANG=bg_BG) the winecfg translations take over and no problem there, just the unicode thing looks like rubbish under the icon. And, has twice as many characters as the text itself, which points to a problem within the control, rather than the codepage (?) - most probably, usage of ASCII rather than Unicode in control itself.
If there are twice as many characters in the text as there should be then you have probably encoded the file in UTF-8. Try to add '#pragma code_page(65001)' at the top and '#pragma code_page(default)' at the bottom of Bg.rc. By default wrc expects the string to be in the Windows codepage for the specified language.
Mikołaj Zalewski