Er, isn't it a bit late in the development cycle of an engine to discover this sort of problem?
Engines and airacrft are not developed at the far ends of an icing envelop. Now that it is realized that the operation intends to use this envelop as often as they do, the engine needs to have a work-around for such an encounter.
Lots of other examples in-service where recommendations were not followed to avoid encounters and where extraordinary action need be taken at the product level