These two worry me a lot. I am not very experienced with Neps, and have never grown this special one, but I think these two things might be a problem.
How good is the drinking water in Sweden? Remember that carnivorous plants need really, really pure water. My water is perfectly drinkable as well, but it would kill my plants very quickly if I used it without running it through my Reverse Osmosis filter. You may need to switch to distilled water temporarily, or test your water and see how pure it really is.
Neps really, really hate being in standing water, which is why most people keep them in pots that drain very fast. Mine was turning black like yours until I used plastic to push the pot up a bit in it's tray, so it doesn't get as wet as the rest of them.
Growing them in an undrained ceramic container is possible, but you will have to be very very careful about the water. What I would do if I absolutely did not want to repot them, and was not sure about the water, is I would flood the pot, then tip it on it's side and pour the water out, gently, until I could not pour any more out. This will leave the media very very damp, but it will not have much standing water, if any. Then, I would simply repeat this process every few days.
Alternately, you could put the plant in a plastic pot, and keep that plastic pot inside the ceramic pot. You would then just take the plastic pot out to water, and put it back in after it had drained a bit. Basically, you would use the ceramic pot as a giant saucer or tray.
Maybe someone with more experience than me can step in here and give a better answer. I'm really worried about tap water and undrained containers...
