Shampa Sadhya wrote:

It sounds good but won't be practical because a huge percentage of people are not very comfortable in English especially while writing the technical words. They can express it very conveniently in Hindi or in their mother tongue. It will further create confusion if English is made mandatory for official use in India.  

The use of English words for technical and professional terms will bring uniformity and avoid chaos. As regards convenience, most English words are more convenient. These need not be translated. I don't feel that it is necessary to translate words like 'affidavit', 'university', 'gravitation'  These words can be adopted in all languages. I remember an incident. Somebody wanted to reach university. He told the auto driver that he wanted to go to Vishwavidyalaya.  But auto driver could not understand. He also asked others but nobody helped. Incidentally, he again said that he wanted to go to university. The auto driver said- okay sir, You should have told earlier in plain Hindi that you want to go to university'.   For many, 'university' is Hindi and 'vishwavidalya' some thing unknown or foreign. 

The best way is to use Roman script for all languages and adopt technical/ professional terms of English. This will be most convenient.