Shipped an anthurium crystallinum (I live in Singapore) wrapped in sphagnum moss 12 days ago from Indonesia. Leaves came wrapped between paper (flat & moist). Very healthy established root system, thick & white. The verrrry end of the leaf tips were yellow/browning with some cosmetic damage already before shipping.

No bugs. A lot of white residue on leaves from seller spraying fertiliser/insecticide. I gently removed sphagnum & put in a low light bathroom + jar of water to let it acclimate for 3days. Then repotted in 20cmx11cm terracotta with homemade well-draining chunky mix of coir, pine bark, pumice, perlite, charcoal & worm castings. gave it a full water through & put it 1m away from my window which gets dappled morning sun & bright indirect light for the rest of the day (see pic below). Didn't let leaves get wet this whole time.

Since then the same yellow+brown on the leaf tips began showing along the outer edges. No sign of rot on stems. The yellow will begin to show (only on the leaf edges) and become more prominent, then it will turn black as yellow 'spreads' from outside in. The rest of the leaf is green & fine.

~5days ago I wiped the white residue on the leaves off with a cotton pad (from the seller's fertiliser/insecticide) + wiped a 2nd round with neem oil + cut off all the yellow/brown bits. But today i noticed the yellow margins are showing again on my leaves :(

I have a moisture meter & only water thoroughly (avoiding leaves) till it runs out the drainage hole, when soil is almost fully dry (~2x so far including today). Singapore has soft water.

P.s., Singapore is a tropical country (v similar to Indonesia, from where it was shipped) with high humidity even indoors (50-80%), so getting water on the leaves isn't a great idea... Would love if someone could identify the problem & what I can do about it :(