For me, I accept the fact that Cymbidiums tend to have ugly leaves and don't give much thought. Particularly if the new growth looks OK, I'd not worry about it. The ugly leaves tend to shed, and not spread anything.
Only now I noticed these were Cymbs...
Leaves like that are perfectly normal, at least to me. Mine are far, far worse than that.
Just don't put them neat other plants.
If you're really thinking of discarding it, I would first take it to a university or local agricultural station to be examined under a microscope. It might not be Phyllosticta. As rbarata and Roberta said, Cymbidiums always have lots of black spots on the leaves.
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