After reading virtually every post I could find on growers who grew N. campanulata well, and those who made mistakes, and relating it back to what I witnessed in the habitat, I think I have narrowed down the do's and don't of growing N. campanulata cultiavation:
1 - In the wild N.campanulata grows on limestone vertical rock, often haning down from icicles of limestone.
I have seen success achieved from a few growers with a variety of media, ranging from burnt earth, to sphagnum.
As it naturally grows in limestone, I think a mix of something that is a little more Alkaline, with a pH of around 8 (limestone dust) could be good practice.
Note that both the Mulu habitat and the original Gunung Ilas Bungaan habitat in east Kalimantan, both were limestone outcrops and N. campanulata grows
around 300metres on both of these. It does not grow on the ground or lower than that altitude.
2 - Being a few hundred metres on the side of the vertical rock, air circulation must be good, and therefore two factors are critical, the media must occasionally dry out between watering and yes a fan is probably a good idea.
3 - Due to the good air flow that I mentioned in point 2, the plants likely never overheat or get to the same level as lowlanders like ampullaria, raff and bical do, just a few hundred metres below. Yet being at 300metres-500metres, it is still low enough for the temperature to be considered warm and i think this is where the confusion has arisen and it mistakenly has been grouped into the Lowlander category. Therefore it should NOT be treated as a typical lowlander and typical lowland conditions will not suffice long term. It should be treated as one of those unique species with specific requirements, like pervillei, vieillardii & madagascariensis
4 - Whilst the media should dry out between watering, for good growth humidity fluctuations/swings that the plant experiences daily in the wild, should be simulated. So I think it is best practice to not grow it in 99% humidity, 99% of the time, like you would do with N. bicalcarata/ N. ampullaria. Swings are recommended. I have seen it grown successfully in constantly low humidity by one grower, but by his account it grew very slow. So I think a good balance of humidity fluctuations are recommended.
5 - And finally, the plants that grew in the wild, received maybe a few hours of direct light, mostly they were sheltered by the limestone and the mist, so full on direct sunlight is not recommended, reports of leaves yellowing out and poor pitcher production have been reported in such conditions. Dappled or filtered light is probably best practice to simulate what they would experience in the wild.