Finally i have done it without using any third party plugin in TinyMCE 4!
Note: Few things you have to keep in mind:
The language works upon the fonts installed in your OS.
Download valid fonts: Indian -> Regional fonts and install it in your OS.
Make sure all the installed fonts are proper and valid and downloaded from a proper source.
If you are using Windows, the installation path would be like this:
C:\Windows\Fonts\
Code:
tinyMCE.init({
mode : "exact",
elements : "textarea",
theme : "modern",
toolbar: "fontselect",
font_formats:"SCiRound=SCiRound;Shonarb=Shonarb;Shonar=Shonar;vrindab=vrindab;Vrinda=Vrinda;Devanagari New=Devanagari New;Kruti Dev=Kruti Dev;Kalpurush ANSI=Kalpurush ANSI;Aruna=Aruna;Haritha=Haritha"
});