What's your question? Ask

They are being overwatered and not receiving the correct DURATION of light. They don't tolerate direct light, but they do like bright light. Window light, even South facing, will not be enough to scorch these plants, and will give you the duration of light that you need. Alternatively, you can try using a small horticultural grade lamp.

As for the fungal infection... It is best to let these dry out very thoroughly down to about 2 inches. Not doing so causes what you are seeing now. Wet Feet=Fungal Infection.

I would treat with a fungicide. this article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm

https://www.gardeningknowhow.com/houseplants/polka-dot-plant/growing-polka-dot-plants.htm

ASPCA calls polka dot plant non-toxic. As with many plants, the amount ingested is a big factor. Almost any unusual food, in sufficient quantity, will cause mild GI distress. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/polka-dot-plant

You will want to water when the soil is dry down to about an inch. This will take a different length of time depending on conditions around the plant, so it is best to just feel it to know when it is time to water.

Water until it starts to run out of the drainage holes, and allow all extra water to leave the container and saucer. It should never be allowed to stand in water.

Here is an article that will help you to grow these plants: https://www.gardeningknowhow.com/houseplants/polka-dot-plant/growing-polka-dot-plants.htm

Your plants may be in shock from the change in environment. With correct care, they should recover. Bright but indirect light is best. You may have it in full sun. They will wilt quickly if allowed to dry out. Keep the soil moist, mist the leaves, and fertilize once a month. If the leaves turn yellow before dropping it's getting too much water. If they drop without turning yellow they need more water.
You didn't mention if you repotted them when they came home - they may be rootbound.

Here's an article that will help:

https://www.gardeningknowhow.com/houseplants/polka-dot-plant/growing-polka-dot-plants.htm

I would cut away the damaged or dead leaves. Then read the articles below to see if you are following the proper care for these plants. If the plants were in the cold for a sustained time, they may never recover. Only time will tell.

https://www.gardeningknowhow.com/plant-problems/environmental/tips-for-saving-cold-damaged-plants.htm

https://www.gardeningknowhow.com/houseplants/nerve-plant/growing-nerve-plants.htm

https://www.gardeningknowhow.com/houseplants/polka-dot-plant/growing-polka-dot-plants.htm

I notice that the container is way bigger than the plants. It is likely that there is a lot of soil that is not colonized by roots, which can lead to overwatering. This is what appears to be the case, here. With this situation, the soil remains too moist for too long, which suffocates roots and promotes infections.

Be sure to let the soil dry out, very thoroughly, down to about 3 inches between watering.

Treat with a fungicide to get rid of the infection taking hold.

These plants will typically lose their color with excessive light. Indirect light promotes best growth, while very low light promotes the best coloration. Direct light needs to be avoided.

Here are some articles that will help:

https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm

https://www.gardeningknowhow.com/houseplants/polka-dot-plant/growing-polka-dot-plants.htm