Wrong Rendering of Sinhala fonts

I tried this with both ibus and scim input methods. the probelm exist with both methods. The default sinhala font come with ttf-freefont has wrong rendering according to the language. But when I remove ttf-freefont its working fine with the third party unicode fonts. But the problem is there are some other important packages get romeved along with the ttf-freefont eg:- printers drivers. 

I suggest ttf-sinhala-lklug font instead.