I don't see anything off about the froglets. But I think that the light and filter have something to do with the others being more active. What is the water depth of the tank with the filter?
I have a froglet just about the size of yours and she spends all her time on the bottom. She swims around from hiding place to hiding place and to eat, but other than that I don't see her much. She has a filter but no tank light. She eats well and is growing. I'm not worried about her one bit. Some froglets are more shy that way. Try adding more hiding places including a floating plant. This should ease their stress and make them want to explore more.
It is probably too soon to tell sex with 100% accuracy at this point, but you might see a cloaca starting to become more prominent in a female at this age. To take good pics for determining gender: Put them in a kritter keeper(or clear container) with no substrate and a little water. Put the kritter keeper on a white piece of paper and get a pic of between its legs from above.