An update to my situation: Both my N. bicals and my N. ampullaria seem to be enjoying the new humid terrarium so far. My older N. bical pretty much "woke up" once I gave it the better conditions, which is always a cool thing to see! I do have a few conerns though:
1) I'm using the tray method to water my new Neps in this terrarium. Since it's so humid, the water barely evaporates, keeping the plants waterlogged all the time. Is this bad for these plants? I've heard on this forum that both of these plants come from swamplands, so is keeping them waterlogged ok?
2) A hairy fungus has started to develop on the soil of my older N. bical. It hasn't actually hit the plant yet. I have some Physan in a spray bottle. Would it be ok to just spray this on the soil?
3) I've been taking the top off the terrarium every few days to get some air to my plants. Other than that, not much air gets inside. Is this ok?