First of all, blade quality problem is very unlikely to happen now, considering China now uses superalloy blades in commercial engines, and the cracks are easily checked with x-ray. WS-15 is by far the most important project, and it is not without sufficient investments. So there is no need to risk just to save some money.
Secondly, given the level of secrecy surrounding J-20 I doubt anyone can get this much details on the WS-15 project, especially from more than one sources. They can write and sell this story just because everyone wants to know about WS-15 but no one can supply any news.
So even though any accidents can happen, we are unlikely to know about WS-15 details. Maybe certain country's intelligence community may know some, but they are unlikely to disclose that to the public either.