If you are a Google Adsense user, it is better to write your content in English. By doing so, you will gain more audience than local user. But If your site is mainly focused on local market where Google does not support the language, it is better not to use Adsense on that site.
Here is the Adsense policy from Google:
So, it is not wise to play with Google guys, They will simply close your account and you cannot get your money back again and also you cannot use Google Adsense on your other sites