I looked up com ml on issues with leaf coloration, and the ones that come up most are not enough acidity in the soil and watering it with chlorinated water. Well, I put it in a 50/50 soil and peat moss mix for acidity and I've only ever given it filtered water. I also fertilized it with a small amount of spent coffee grounds. They're only sitting on the top, so the majority of roots aren't getting any of it. This started a couple weeks ago. The leaves are soft and moist and don't feel like they're about to fall off. I put a plastic bag over the leaves with a few spritzes of water for a few days but so far there has been no improvement. What is going on? It isn't about to die but it looks really unhappy.

Soggy soil and/or root rot: when roots are chocked out by water-logged soil or are rotting away nutrient intake is stunted and hence it appears like the plant is suffering from all sorts of nutritional deficiencies, or is planted in alkaline soil or will display a bewildering array of symptoms.
The burnt leaf tips are probably due to either the same issue (especially root rot) or too high light levels: the reason the miracle berry is not widely grown around the world and it's mostly a curio is it's a very fussy plant when it comes to growing conditions.

Okay. It lives in a corner away from direct light, so I'll put it in a larger pot with dry soil inside.

Wait for the potting compound to dry up a bit before repotting to avoid stressing the plant even more.