Hello

First of all there's no percentage barrier to be eligible for JEE mains

But yes,

To be eligible for NITs, IIITs, GFTIs , jee advanced( for iits) one needs at least  75% marks in aggregate in class 12 if belong to general or obc category or at least  65% marks if belongs to SC/ST or  must be in the top 20 percentile in  class 12 examination.

5 Subjects to be considered for calculating aggregate percentage are :-

*Physics

*Chemistry

*Mathematics

* A language

*Any subject other than listed above

So , it is not mandatory to include in English for calculating the percentage and so yes you can definitely consider Hindi to calculate your aggregate percentage in place of English to be eligible for NITs etc

Thankyou