I would not worry about PH. It is not as much a factor as water quality. It sounds like you are on top of it though. These frogs are more sensitive, skittish, and fragile then the Clawed frogs. I have had great success with them in the past and huge failures since. Very frustrating. They are worth it though once you get a good group and everything running smooth. You can try to entice them to eat other and better foods perhaps. Mine always find mysis and spirulina enriched brine to be top notch and irresistible. I really hate bloodworm as a food for these guys. The few times I used it in the past my frogs paid by dying of bloat one by one.
I find that giving them more hiding places actually makes them more active. They will eventually be out and about once they are comfortable though.