I too am able to use the Mangal font in Word, however, Mangal does not show up as a font option when I try to select the editor font.

I think it's because the editor uses only ANSI fonts and not UNICODE. Consequently, you would need to install one or more ANSI Hindi fonts. You can then select one of those fonts for the editor, or simply as the font to be used by MediaLab in the preferences.

Note that this is different from choosing a font such as "Arial" and then selecting a script such as "Hindi". I have not seen the "Hindi" option available for a standard font script--I'm not sure why.

So a workaround would be to use an ANSI font that is Hindi by default. That is, the Hindi characters map directly onto the regular US/Western European keyboard.

To see what I mean, to going to "Preferences" in MediaLab and edit the fonts to be used in the experiment. Choose an ANSI Hindi font and run the experiment. Even if you have typed the characters in English in the Experiment Editor, they will appear in Hindi when the session is run. You could also set the Experiment Editor to use the same ANSI font--but that will make everything appear in Hindi--not just the question wording.

Not sure where the best source for ANSI Hindi fonts is. I was able to install the set below by trying the trial version of Baraha's text editor. It installs some of the following ANSI Hindi fonts you could try--

BRH Kannada
BRH Vijay
BRH Kailasam
BRH Bengaluru
BRH Sirigannada
BRH Amerikannada
BRH Devanagari
BRH Tamil Tab
BRH Telugu
BRH Malayalam
BRH Gujarati
BRH Gurumukhi
BRH Bengali
BRH Oriya

Their website is located here http://www.baraha.com/. They have some interesting looking utilities and editors that might also be of additional use for Hindi users.

Hope that helps!