Compliments on the set up as well! My only suggestion is maybe to get a little fish tank air pump, as tiny as you can get just to pump some oxygen into the water and keep it moving. Hide the little pump under the rocks in the pond and the air bubbles will push up from under them and keep it from going stagnant. Red Bellies do great with those little waterfalls as well that filter themselves.

It shouldn't stress the little toads and even might make them less skiddish when you approach in the end.

Oh! And don't put them with crabs - crabs will try to pick at anything you put them in with, landing you with toads with holes in them. If you do set up that air pump try some little guppies, the toads might even try to chase and eat them. The guppies should pick at left over food and waste in the water.