Hi again!
maxima: don't fertilize it, neps like fertilizing but only when it's done in proper ways, and if you are not experienced, I wouldn't play with that, insects are enough. I said the opposite: that maybe you fertilized too much, but if you say you didn't fertilize, then yes, it might be too low light level. I excluded that before because it seems to me that the color on the pitchers is fine, they just look very small when compared to the leaf. Maybe it's just an ugly form
Also, no appendage under the lid, not very hairy, the red stem and leaf base make me think it's a hybrid...
miranda: the story is: in the 80's a dutch nursery spread around the world many hybrids (and the first massive distribution of carnivorous plants), most with wrong labels
One of these hybrids was N. x mixta, which is N. northiana x maxima. This nursery also had the strange habit of giving to some hybrids cultivar names, without registering them as cultivars though, so these names were just not-valid nicknames. So he named one of these N. x mixta as N. "Miranda". Some people even think that what he sold with that name was actually N. mixta x maxima, and that could be! Recently some people (?) repeated that same cross (mixta x maxima or northiana x maxima? Who knows...) and spread the plants as N. "Miranda". But their plants are of course very different from the dutch plants, because different parents were used, and the whole range of seedlings was spread in cultivation. The dutch nursery, on the contrary, spread just one or few selected clones, produced by the millions in TC, so they all looked the same. What's your plant? A hybrid
It could be a miranda, who knows, a small plant of a new clone, don't know... This is a drop in the sea of the reason why I don't get involved with hybrids
A part from recent times (when professional growers made well-planned hybrids) loooots of hybrids have been made simply because one guy has a species in flower, he will look for ANY other species in flower, from some other grower around the world, and they will share ovary and pollen to cross them and make seeds, just for fun. Then they will spread the seedling in cultivation, often with a wrong name (because the parents had wrong names already, or because people don't care so much if the label should be "maxima x ventricosa" or just "maxima") and many years later a guy in Argentina is in your situation
alata: the same dutch nursery spread around the world millions and millions and millions of N. x ventrata, labelled N. alata. All growers who have a minimum experience know that plant too well, as from Italy, to Singapore, to Japan, to Australia, to the US and Argentina, on the market you will find that same plant, labelled N. alata. This hybrid is N. ventricosa x alata. N. alata is quite different, just check the web. The peristome of N. x ventrata will become lobed as soon as the plant grows up, if it remains in good shape.
Get your plants used to as much light as possible, as long as the humidity remains above 50%. "Get used" means that the first week you can give 2 hours of direct sunlight, the second week 4 hours, etc. Until you give 12-15 hours of direct sunlight. Any red color you see on leaves and stem is fine. Many growers are afraid of giving too much sun to these plants, and that's the most common mistake. I don't refer to Italy (you might say our sun is milder), I say this after having seen most species growing outside, in open gardens, in Sri Lanka
Keep the soil always damp, using rain or distilled water, and don't move the soil away from the roots, just give bigger pots when the roots start growing in large number along the sides of the soil lump. If you change the whole soil lump, make sure the plant grows in very high humidity for the following few weeks, to recover from the stress. Any soil can be used with similar results, as long as it contains the usual basic components: peat, sphagnum, coco peat, mixed with coarse ingredients like bark, perlite, coco chips, pumice etc. These are general rules, good for beginners and common plants found on the market, so there are exceptions