They are VERY easy to grow from leaf cuttings! But it takes approx. 3-4 months until you see baby plants. I've started 4 pots so far that way over the past 2 years.
It doesn't sound like you did anything wrong. Some CP dealers DO add a 14-14-14 osmocoat pellet or 2 in when they re-pot. I believe Green Jaws does that and California Carnivores too IIRC. When I re-potted my ceph a few weeks ago half the pitchers died but about 5 new ones started growing almost immediately.
Maxsea works fine for most CPs. California Carnivores recommends Schultz cactus fertilizer for pings now. Youcan also put one Osmocoat 14-14-14 pellet in each nepenthes pitcher as well once a month. Also Sarracenia. Add a little rain or distilled water though if you do.
These are so easy to grow. Mine grow in a west facing window. They sit in a shallow tray of rainwater at all times. They get some afternoon Sun. I'd say stop spraying them. How much BRIGHT light do they get? I would stop messing with them and leave them alone. It may be too late by the look of them right now. Hard to say. Time will tell. You may want to get another one in the meantime. They need bright light to produce dew as well. Lack of dew means not enough light.
The dying trap probably just reached the end of it's life cycle. Plenty of room in that pot for another year I'd say. Repot if it's been in that soil for at least a year or 2.
It's totally normal to have some stay green. I'm waking mine up the past 2 weeks from fridge dormancy. Been doing it for over 12 years now with no problems at all.
Buy a package of "Mosquito dunks" at the garden center. Put one quarter of one in your watering can. This will kill the larvae in the soil and stop future generations. It is all natural and safe. But give it some time to work. Use sticky traps and manually kill the adults.
I grow one and it's currently going through a growth spurt. I grow it in a west window, water level up to the top of the pot which I allow to occasionally go half way down the water container then I refill it.