Using the XIRR function, the return for that bond (INE721A07OB9) indeed come out to be around your estimate (8.64%) -
The actual YTM would be a little lower because the XIRR function assumes that all interest payouts were re-invested back into the bond (which might not be the case). As per the IndiMoney website, this bond has a YTM of 8.20%
For absolute return, I did the calculation by adding all the interest payments and the face value of the bond ( 100000 + 29 * 760 = 122040 ) and then subtracting the initial investment from it (122040 - 102000 = 20040) and finally dividing it by the initial investment ( 20040 / 102000 = 0.196470588 * 100 = 19.64%)