Hey
Until the fecal comes back there's not much known about why the frogs not feeding and how to resolve it. I'm never had any problems with bullying, usually the competition makes them more eager to feed, if anything. If you didn't supplement the diet correctly then it could have MBD and finding it hard to catch prey or move about, but unless any signs of deformity are there then blood tests and x-Ray's would be needed to know for sure.
A planted tank that size might be quite hard to keep clean for whites, not much floor space for planting and for waste to get broke down in, could lead to infections. This is only my opinion, I would just go larger for planted tanks for them to work best. The 2.0 UVB bulbs should not be labelled as UVB bulbs. Only if they are mounted inside the tank are they any use because the screen top filters up to half of the Rays out and a 2% output is low so not much power will make it through. If it were me I would use a 5% and a heat lamp during the day for a basking spot of 85F. I gut-load insects with fruit and veg mixed with calcium and then every few feeds a commercial diet and dust with Repashy Calcium Plus every time. it's easier than the normal supplements which can't be used as frequently and need to be used on set days (which recommendations vary) to avoid over supplying. For the supplements you have I think the usual is twice a week for juveniles and once a week for adults with the calcium mixed with the multivitamin, one should have D3. Someone else might be able shine some light.