I would say Indo-Islamic mix of Taj Mahal is somewhere in the 20/80 range, with 20 being Indian. The overall impression one gets seeing the Taj is not of Hindu or Buddhist setting.
i dont like categorization of indian architecture on hindu and buddhist terms, there are rajput palaces, there are even ahom palaces, there are also nepalese architecture which too has been given a colour of islamic or mughal influence, based on what evidences are they declared islamic?
if taj mahal is 20/80 range islamic than what about rajput architecture and based on what proofs you give 20/80 range
i think what we are dealing here is an educational and scholarly dilemma.