The holy Quran which Almighty Allah revealed is in Arabic language. Also in the holy Quran Arabic has been mentioned as its special characteristic. Hence the holy Quran written in English or Hindi etc shall not be equal to the holy Quran revealed in Arabic. Rather it shall be its incomplete explanation as in any other language of the world the necessary and fundamental characteristic and attribute of Arabic is not possible. Hence as per the Ijma (consensus) of Ummah it is haram to write or read the holy Quran in any language other than Arabic.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband