I think the dry heat of inside might lower the moisture content of the bow,, keep the bows in a part of the house that is not that hot should help,, I dont think it is so much the cold,, but just overly dry conditions,,
couple of winters ago, I had a sinew bow in a room that was the warmest and heated,, the bow blew up when shooting but when I put the moisture meter on it,, it was below 6%,,,, I live in hight desert, so for me it was more a moisture content than winter conditions,,
I have hunted with my osage bows in the single digits with no problems,, I dont think any well made self bow will have a problem with cold weather hunting,,