Light intensity is a main factor, and nutrients to balance. You have primarily stem plants, which need brighter light because they are fast growers, and there is evidence the light may not be that intense because the lower leaves of the stem plants are dying off. And this is almost always light. This has another aspect...colour. Red leaf plants appear red because they reflect red light. Red and blue light are what drive photosynthesis, with red being more needed. The afore-mentioned issue suggests this is not going to work because red light seems to be at a minimum now.
For these reasons, I would look into less light-demanding plants that are rosette type, like Amazon swords, crypts, pygmy chain swords. You could get some of the reddish-brown crypts, they might do well, they did for me with my moderate lighting.