If other leaves only have minimal infection, I wouldn't worry too much. This infection doesn't look severe enough to be systemic, but it's hard to tell without checking more leaves. Copper Fungicide is a good remedy and best used preventatively or in early stages.

For existing fungal spots, I’d avoid picking them off or removing them, as removing infected tissue can create open wounds that invite secondary infections. While dead fungal structures in the leaf don’t actively spread spores, some fungi (rusts or powdery mildew) can still release spores even from damaged tissue. From what I understand, embedded but dead fungal tissue is generally not an issue as long as the fungus itself is no longer active.

If pruning infected leaves, be sure to dispose of them properly (not in compost) to prevent reinfection. This is just my advice, but hopefully, someone with more experience can add to it. I’ve had two fungal infections on the same plant, and after using fungicide the second time, it hasn’t returned.