Overall your tank looks good, but I have a couple of questions;

It appears that you have hydroball (clay pellets) under the gravel separated by some sort of divider in the water section: why?

My firebelly toad tank was also about half land/half water, but I kept the water level around 4-5 inches deep, with easy access into and out of the water section. My toads not only loved to swim, but also appeared to enjoy actually diving into the water area. It also, appears that, with all that java moss, your toads are unable to actually swim anywhere.

You might want to consider making your life a little easier and remove alot of the excess (gravel, hyrdoballs and java moss), which would open up the water area which will make water changes easier.

I agree with Karen, your toad's behavior sounds like they are hungry. I strongly believe in books and doing research, but the toads are individiuals, and only through trial and error will you learn just how much to enough to feed yours.

This is part of the fun of keeping them.