[Tindomul]

I would check for pests. Mites could be your culprit. Clean the leaves with a white paper towel and see if you get a red smear. Or if you have access to a powerful maginfier put a leaf under it and search for red spider mites or their eggs. In anycase, clean the leaves with alcohol thoroughly.
I dont see any sunburn. And misting is fine. When misting, your main objectives are the exposed roots, to wet them till they are green, and maybe the leaves if its a hot day or the plant is in a well ventilated room. I myself rarely mist the flowers or the leaves on purpose, but I dont avoid them either. I just go for the exposed roots and the top of the substrate, and if anything else gets wet I don't bother drying it. They say not to let water accumulate at the crown, but for me this has never been a problem because it always dries out within minutes.