> English pronunciation <-> spelling is actually pretty predictable as long as you aren't considering letters/phonemes in isolation.

Yeah, and you also learn the etymology of each word. With plenty of exceptions.

I learned English mostly as a written language, by reading books. And for _years_ after moving to the US, I had a problem with pronouncing words that I knew perfectly well how to spell.

E.g. I was confused when a doctor told me that I had "neumonia", even though I knew the word "pneumonia" perfectly well. Or that "gearbox" is not pronounced "jearbox".

> but when it is of Greek origin (or at least came via Greek) it is pronounced "k"

Or Latin. I volunteer to teach English to refugees, so my rule of thumb: if a word is similar to a Russian/Ukrainian word then it's pronounced with a "k" sound. But there's also a bunch of French words where "ch" is pronounced as "sh".

But really, the main rule is to just memorize what the pronunciation is.