I wonder if the integration works allowed Eyrie Eye to guide the PL-15E's via datalink. Some wild conjectures:
1, Indian pilots assumed they were in safe distance given their experience with amraam yet unaware of PL-15E capabilities.
2, PL-15E's were guided by datalink and no fire control lock, Indian pilots were oblivious until missile went pitbull. If they had awac support their awac should be able to warn them of approaching missiles, but then it is possible awacs were under EW suppression.
3, It is possible both J-10CE radar and PL-15E seeker are using some sort of LPI mode that the French avionic suit were not able to pick up on.
Whatever the real scenarios were this event is a treasure trove for both Chinese and western intelligence. I won't worry about it leaking Chinese capabilities too much though as things changes so fast in the electronics front whatever intel gathered would be obsolete in the next conflict