CC doesn't appear to be able to insert items in campfires.
Support could be added by making campfires an inventory peripheral, or turtle.drop.

This is an interesting one, and I'm not quite sure what to do here. Campfires cannot be interacted with via vanilla automation (hoppers/droppers), and I think this makes sense - unlike furnaces they don't require fuel to operate after all.

I think it makes sense to follow this in CC, and not allow item inserting/extraction. However, maybe the other inventory methods (size, list, getItemDetail) could be supported.