Silver mottling/spotting on leaves in terrarium

[Paul Mc]

So I have a few issues going on actually, lol...

My original terrarium build apparently didn't have enough air flow so almost everything died from rot. Redesigning it with more air flow allowed those that survived to actually thrive! Example, one leaf left on my Dracula lotax and suddenly three more leaves appeared as the old leaf died off. Given the success, I bought a larger terrarium so I could possibly have a few more in there. Unfortunately, it means regulating everything all over again as well.

Recently, I started noticing a silver spotting and mottling on a few leaves. I sprayed using fertilome Triple Action Plus for insects, fungicide and mites as I assumed it was a mite issue. I left the door and top open so the chemical fumes could be released.

Since spraying over two weeks ago followed by two more spraying sessions weekly, the mottling has continued to spread. One Masdevallia dropped all but one of it's leaves. Two more Masdevallias are also dropping leaves, but both were recently repotted and only one has the silver leaf look. I am assuming the dropping leaves are from repotting and possibly the chemicals getting on the roots.

Would anyone be able advise with what they think is going on and possible treatments? Thanks!