Try through this link, I am hopeful you can submit your content in Hindi.
http://www.google.com/inputtools/cloud/try/
Can we write the text in Google and copy-paste that in the editor here? Will the admin accept such articles that are copy-pasted at least for other languages apart from English?
Yes. I wrote all my Hindi articles using Google transliteration facility. This is also formatted there. There is no way to save the article in Google. So you may have to copy paste several times from Google to Boddunan. and save. Hence you must be careful about font size. This should be same every time you copy paste. When you have copy pasted entire article, submit the article.
Copy paste from other sites and M.S. word is not allowed. But this is allowed from Google transliteration facility for Hindi and Telugu articles.