For neone who has the same issue. I have figured out a way to type Devanagri script in the WYSIWTG editor of CMS.
To start with install the fonts that you want to type in. Lets say you want to type in Marathi or German or chinese. Install the fonts in your operating system. You can double check if the fonts are installed by trying to use this font in a Word application.
Now for entering your text in the customized font; you will need to add the font you installed to the drop down menu of fonts available in the CMS Editor.
Navigate the to the path
Edit the editor_template_src.js and add the font to the nFonts variable. Like ;Marathi=iitmhind. This will add the marathi font in the drop down.
When you refresh the CMS editor you will see this font in the drop down and you can select the font and start typing in Devanagri script.
Hope this helps