Fungus, but what?
 

Hello comrades,
I'm attaching pictures of a cattleya leaf for your inspection. It's the most recent growth on the plant and is, as you can see, afflicted with what I guess is a fungal issue. The older leaves don't have the discoloration that this one shows.

Is this something I can conquer with chemicals, or should I ditch the plant? It has a good root system and fat healthy psuedobulbs.

Thanks for your input!

What does the back side of the leaf look like? Sometimes scale establishes itself on the back of the leaf, sucks juices, and you end up with spots like that on the front. Figure out what is going on before you try to treat. I don't think it's fatal, especially if there are good roots and the older leaves are OK.

No scale, no pests on this one. Leaf is smooth on both sides, yellow spots are not sunken, at least not yet.

Bush snails maybe? They attack the leaf cuticle, not being big enough to chomp through. I think that you need to keep an eye on it, separate from other plants. Perhaps someone on the forum can make a diagnosis. You can't treat until you know what it is. To me, looks more like pest damage than fungus.