I am sorry to read that your family members had to deal with all that! Canoa is not one of the best places to stay overnight. I hope they will retrieve their bags without missing any items. I never took the bus in Costa Rica, I always drove in there.
I did have a similar thing happening while I was in Ecuador by bus. At the end of my bus ride from Quito to Cuenca, I had all my bags, but some of the things inside were stolen.