I would definitely change out your substrate to a dirt based one. Bark has poor water absorbtion quality, which will mean your substrate will either be flooded or pretty dry. It is also make for a very poor nesting site, as it would be very diffucult for the brevi to dig in the bark and construct a nest. Your plants, which I also recommend you add a lot more of, are going to have difficulty growing/rooting in the bark.
Just some Thoughts,
Danny