well, i dont have the answer, but related to this is the lore that back in the piston-only days, people would routinely punch through any storm and then when turbines came along people started to fly aroudn them.
not surprisingly, i have only heard this from old grey piston fans....
It is normal for many SOPs to require that the pilots turn on the ignitors for constant operation in heavy rain. The water going through the engines MAY cause a flameout. Keeping a high N1% and the ignitors on will help alleviate that problem.
It's not much of a problem today with the new turbofan engines. Much if not all the water gets "slung" through the bypass ducting by the fan (N1) before it can enter the gas generator section of the engine. There must be the possibility of heavy rain or hail causing flame-out because our SOP says igniters on when in the vicinity of thunderstorms- don't know if that's for possibility of heavy turbulence causing disrupted airflow through the engine, heavy rain/hail, or most likely a combination of both.
So, yes. Turboprop airplanes are subjected to this too... Ignitors do help a bit in that, should a flameout occur, the ignitors could refire the engine.
Reasons for having ignitors on around thunderstorms are the possibility of encounter with sudden precip, but also due to the possibility of encountering severe turbulence and shear in the vicinity of thunderstorms which could cause compressor stalls or flameouts.