Vanda fungus?

[Charles]

I am no expert on disease, but I do grow a mean Vanda. I think the dark discoloration is tanin from the oaks. That one oak leaf in the pic shows a dead "oak tea leaf".It settles into the leaves and leaks out to stain the plant. I have one that came from a grower with bad water. My stains look like a toilet bowl with lime stains. It's whitish instead of dark like yours.
The pic with the black spot is another matter. Cut that leaf off as best you can and use cinnamon on the wound. Normally, this kind of thing could be ignored if the plant is currently vigorously growing otherwise. Use a hose to water them in the summer. Soak them when it is hot. The heat of the day will dry them well enough. And make sure they get enough sun. Vandas like sun, but introduce slowly. The leaves should be the "right green". This indicates proper light.
PS. The one black spot on the bottom leaf may also be from heat damage or trauma. You may want to simply watch for a spreading effect. If it spreads, cut.