i like the fan mounting, that's cool. i`ve never use a humidifier at all. i will point out the an observation, by adding the extra lights the heat should go up some that will increase evaporation, which in turn raises the humidity, then adding the humidifier you have should have some wet air in that cabinet. i not saying that's what is causing the droopyness, it may just be the transplant, every time you move them it takes a few days for them to acclimate to the new digs so give them a bit and see if they don`t bounce back. this being your 1st shot at this is the reason i pointed out that about the humidity. i`ve never had a need to raise the humidity that much, in a small space with the heat of the light can cause a lot of evaporation that you just don`t think about.
everything is looking good so far, it wont be long and those seedling will be stretching out.