My thought is, if the indoor temperature remains at 59ºF the plants should be okay as long as they are getting enough light. I'd open all blinds, curtains to allow as much natural light in as possible. I agree with everyone else in that the foliage should never touch the window pane, winter or summer. Since you are in Western Tennessee, as the winter progresses I'd think the indoor temperature will drop well below the current 59ºF unless you turn the heat on; tropical plants will not survive cold temps for extended periods.
Although our database shows minimum cold hardiness for as zone 9 that is an error because they would not survive outdoors in winter.
For
Dwarf Umbrella Tree (Heptapleurum arboricola) the database shows zone 9 also and they will survive colder temps in winters outdoors here in zone 9 but only for short periods.
Same for
Christmas Cactus (Schlumbergera x buckleyi) but extended cold and freezing temps would likely kill them.
Same for
Peace Lilies (Spathiphyllum)
Heart Leaf Philodendron (Philodendron hederaceum var. oxycardium) which will definitely get stressed with prolonged low temperatures.
The Peace Lily can take low light situations as well as the Philodendron but the others prefer a lot of bright light to flourish.
