Changing search engine language would not help. Changing the Google search to some other country's Google search, say Google Netherlands would not help either. Changing Android system level or Keyboard language would not help too. The results are tied to geolocation. Shekhar Sharad on Google India Blog noted:
Now it’s easier to switch between English and Hindi with the launch of a new tab on Google Search for mobile. Available in States with significant Hindi-speaking populations, this new feature gives you a way to flip between English and Hindi when using the Google Search app and Google Search on most browsers on your Android or iOS mobile phone....
This new tab search feature has just started rolling out for Mobile users (on all browsers except UCBrowser and Opera Mini) in Bihar, Chattisgarh, Haryana, Himachal Pradesh, Jharkhand, Madhya Pradesh, Rajasthan, Uttarakhand, Delhi and West Bengal and will improve over time.
It is probable that you are either in those Hindi speaking regions or are using a proxy/VPN server located in those regions.
You can verify this on your own. Use a proxy/VPN server located in a non-Hindi speaking region, such as in Bangalore, Karnataka, and you would note that the flip tab is not available anymore. Change the proxy server to a Hindi speaking region, such as in Delhi, and the flip tab would return.