Definitely not sunburn. I think its some infection or pest, though I'm not sure what, probably pays to separate it from other orchids. Good luck, I hope it recovers
nettle
Cut off the flower stalks but don't chuck them. They are your best hope. There appears to be a little keiki (orchid plantlet) on one of the stalks and you should try and get it to grow roots as it is your best hope for the orchid to live.
Your ferns are beautiful! What maidenhair is that first photo cos its huge and I love it
Yea I love those both too, another of my favourite are shield ferns, for their beautiful brown and dark green colours, unfortunately I wasn't able to keep mine alive which was sad.
Anyways here's an update with more of my ferns I'm growing:
My family heritage staghorn (originally my grandads):

Some NZ native maidenhair (Adiantum aethiopicum) and another native fern I forgot the name of (bottom left) 
Some wild native Rasp fern (Doodius australis) looking lovely and pink. Who's growth I've been encouraging:

There's lots of wild ferns around to, including giant tree ferns. These photos here are just the ones I'm currently somewhat cultivating.
Maidenhair (Adiuntum something):

Staghorn (Platycerium bifurcatum) and some little hen and chicken ferns in a tarrerium (Asplenium bulbiferum)

Nephrolepis (back), and 2 mystery ferns (bought them in an unsorted clearance lot):

I've got some of other ferns outside and in other places, but its dark rn so I can't take photos. Will post them tomorrow when its light outside.
Its so hard to pick a favourite I love them all so much. I'd like to try to grow some from spore soon, would love to know what ferns your growing/your favourites too
someone has been trying and it looks like it has potential if it keeps on being developed: https://github.com/Fancy-Mumble/FancyMumble
Yea we can grow lùcuma here to (my uncle grows some), but Im not a big fan of it. Though I haven't tried one since a kid so I should try it again (lots of my other food preferences have changed). How do you like to eat them? I've heard they are best in smoothies?
Yea they fruit great, we haven't harvested any yet but they should be ready soon. (Or now I better check). They are so delicious
I'm not quite sure what you mean by elevation, But elevation would be only slightly above sea level and plantmaps.com says I live in zone 10b.
We live on the very limit for apples, only golden delicious and some cooking apples seem to do really well, other varieties we have don't produce much and are vulnerable to pests. I hope climate change doesn't skrew my apples over in the future but I think it might.
off the top of my head the ones that we grow and are fruiting (New Zealand):
Fejois (tons of em), persimmons, guavas, bannana, lemons (just started), avocados (nearing the end), quinces (gotta make jelly today), apples (we have picked golden delicious and cooking apples will be ready soon, I'm going to make some cider), figs (nearing end), Casimiroa, tamarillo, rocoto chilli. I think kiwi fruit are fruiting too but we don't grow any.
Use them to predict the weather! Their scales close when its humid (predicting rain) and open when its gonna be sunny.
graphite looks promising but is still in early days