I have a pair of these charmers, and I suspect that burrowing occurs at lower humidity levels; when the humidity's up, they are usually at the topmost corner of the glass, but I have seen them burrow here and there. Another possibility that I have read is that burrowing/climbing behavior is dependent on which exact species one has.

All I know about breeding, other than that it's not been done (yet) in captivity, is the following: "As far as is known, a pair while in amplexus burrows backward into damp soil of the bans along water and there deposit a small number of large eggs. There are no large breeding congregations. Embryonic and larval development are slow. When hatched, the larvae wriggle into the water close byu, often to jungle streams, but also into any small watering hole."

[The above excerpt is from The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium. Ed. Jerry G. Walls. Trans. U.E. Friese. T.F.H. Publications inc.; New Jersey, 2000. (493)]

I imagine that, to breed these guys, one would have to dig up tadpoles from the soil and place them in a breeder tank that had a wet bank along a water body that they could drop into when they are ready to. I've heard a lot of mating calls, but I haven't yet witnessed amplexus. It's possible, though, that I have dead little tadpoles in the soil of my tank. While I would love to rear tadpoles, I don't want to tear up my tank when I don't even know where I'm looking.

Good luck to you. Please share whatever info and experiences you come across; there's not too much reading material on these little guys.