All survived just fine. If it is only occasionally below 30 in there, you could always bring the plants inside for the night. I have grown N. vieillardii from seed that is happy in a terrarium under lights. It seems to be a slow grower under these conditions but is producing healthy traps. Temps are pretty constant, maybe 80 or so day and dropping at night maybe 10 degrees or so.
Terrarium is closed in a house with central air.
Planted in live sphagnum, way too wet by most growers standards, but standard treatment for my plants. Hope this helps. Tom in Fl. Now I have another outdoors in a tank with highland Nepenthes. I have heard this before and never understood the implications.