Which rock have live under all this time. Let see there are at least 180X J11B using WS 10 that mean 360 WS 10 engine Then there are 170 X J16 =340 WS10 engine Total 700 engine flying since roughly 2000
20 years of accumulating experience with 1 single known accident
I say that is complete success It take 20 years for engine to mature I don't think WS 15 reach that time limit yet development is sometime mid 1990's
Ws15 is already in product just last month so eventually good things are coming. At least in regards to development, they are slowly getting there unlike the f-35 which seems to have one disaster after another these days