I've made some apricot jam and I'm happy with the consistency. I heated the jars and filled them with hot jam. Unfortunately the jam cooled before I got the lid on. Can I put a cellophane lid on cold jam?
If you want the result to be shelf stable, you need to follow a proper procedure to either process the jam in a water bath or in a pressure cooker. Just placing the lids on the jam (either hot or cold) is not considered safe. Your jam is fine if you want to store it in the refrigerator, but not otherwise.
Using cellophane with hot food is not ideal, since it could release potentially dangerous chemicals into your food. It's designed to handle room-temperatures or below, not higher.
It also depends on what kind of cellophane you are using, since they don't have all the same composition. Some are more prone to release chemicals into food than others (go with PVC-free ones to be safe)
I would not recommend using cellophane for long-term storage anyway.