Hi, I use carob powder for anything that says cocoa and it always works fine eg custards, cakes, biscuits, children's treats etc. Just a slightly different taste.
I've never used or even heard of a carob syrup - is it just a sugar sauce with carob powder instead of cocoa.
I do use Carob buds instead of choc buds, but they are not sweetened so do give a different taste.