I keep my red-eye leaf frog tanks as simple as possible. I provide an artificial plant per enclosure. The adults rarely use the plant, often they sleep on the sides of the tank (as do the blue-webbed flying frogs). The froglets use them all the time.
I recently changed out the paper towel substrate for ground coconut. After reading John's post on the toxicity of paper towels and losing red-eye froglets for no visible reason, I came to the conclusion that the small, fragile froglets could not handle whatever chemicals that are present in paper towels. Adult frogs don't seem phased by them.
The transition seemed a little rough on some of them at first, but they have all adapted well and doing great so far. They look healthier/fatter. It's too soon to say whether or not I have solved the problem or not, but its looking good so far.