Never grew in coco so pretty much talkin out my ass but i know the plant so here goes. Coco and perlite? I dont get that, coco is so dry and perlite is solid air basically so my first question to coco growers is why not coco and vermiculite? There, throat punch me. Second, over and under watering looks about the same to me, wilted droopy, dieing ; but underwatered plants come back in a couple minutes so put the coco perlite in a bucket of water. If it starts praying, good, otherwise the coco dries out quick, no loss. Maybe a couple dunks will flush it too. My advice, your grow.
Edit: if you think its underwatered maybe those roots are thirsty enough for a pan of water. From what i read of coco, the top is usually dry so they cover with clay balls to hold moisture. Fart noise