You are right, IAF does love the r27, but the r27ET. R27 ET and r77 rvv sd have overlap in performance map, while rvvsd has a larger performance map. If IAF orders Rvv sd, then r27et is redundant, thus my doubt.
R27 EP might still come. Actually in testing r27ET and R27t came above the rvv ae we have in stock.
R-27 and R-77 are two different classes of missiles. So there is no redundancy there.