I think your plants are doing ok. Some of the older leaves are fading because the plant needed more N. You cant really fix that anymore. Looks like most of the plants new growth is a luscious dark green, keep it that way.
If you wanted to make things easier on yourself next year, try growing them directly in the ground. I would till the soil and prep it with a few bags of your choice soil, amendments, etc.
You will have to start your seedlings a little later, so that the plants dont outgrow the space. You could also try scrogging and pruning them in order to keep them at a manageable size for your greenhouse.