how to increase the coverage of wordnet using wikipedia
You should look at Open Multilingual Wordnet (http://compling.hss.ntu.edu.sg/omw/).

They used wiktionary (not wikipedia, because wikipedia lemmas are nouns only) to get translations and synsets. EDIT: In the extended version, there is also a Hindi wordnet with 3,593 synsets, see http://compling.hss.ntu.edu.sg/omw/summx.html

There is a non-open Hindi wordnet at https://catalog.ldc.upenn.edu/LDC2008L02.