i'll take a shot. i agree 6 bullfrogs are way too many for a 10 gal, even if newly metamorphosed. wild bullfrogs jump when startled. they may have damaged themselves against the glass. the only way i would keep native frogs is outside in a enclosed pond. enclosed to keep out raccoons.

one thing you might do is paint the outside of the tank glass so they don't get startled or think they can jump through it. i just think its not possible to keep this kind of frog enclosed and you are proving it. try keeping just one alive for a few months first, if that doesn't work, you should stop. i also recommend frequent 100% water changes, with 6 frogs that would be once a day.

the 10 tank should be ok for the fire belly toad, but just barely. i kept 6 in a 65 gal corner tank which was 8" of water and land with live plants on a shelf i built over the water. a water pump sprayed the tank water over the plants planted in sphagnum, which acted as a big biological filter as it dripped through it. it was too good a set-up, as they had many many babies, but that is a whole 'nother story.