Does Jio Phone 2 supports the Bengali language?

Yes, Jio Phone 2 does have the rear camera flash. 

Yes, Jio Phone 2 is a dual sim mobile phone. You can use 4G sim card slot with the Jio sim and another slot can be used with 2G network sim card. 

Yes, Jio Phone 2 does support the Punjabi language. 

Yes, Jio Phone 2 does have the support for the Kannada language.