My zygo seems to do pretty well in higher temps…definitely mid to upper 70s when the lights are on but in the mid 60s or so when off. I do see a bit of leaf turnover but no real spotting. It does seem to be a super fast grower so may just be the way it grows…not sure.
Try spraying the leaves every day with brown Listerine. That is what everyone in my orchid society has been advising for fungus issues. These tend to be happier out of direct sunlight and in temperatures in the seventies. Also, if the plant is indoors, try to water from the bottom or under the leaves (and keep the water off of the plant as much as possible).