Problem with game translation

I m currently making a translation of the subtitles into my SVK language but keep running into problems. How can I create a localization UI_Fonts pack which will cooperate with the game?
I created new gfxfontlib.swf and fontEn.swf files with these embedded fonts: WillowBody,normal,Compacta Bd BT,normal,Chintzy CPU BRK,normal
and I packed into upk file in UDK, but when I run the game the fonts are not loaded which results in squares instead of text (view image)