What to do next?

It currently doesn’t work (might in experimental) but it probably wouldn’t be too hard to add a couple lines of code that save whether or not there’s Cold Air in each tile when it unloads, and then keep it frozen when it reloads. That does mean that if the cooler ran out of power and then unloaded the food would still be cold, but that’s a pretty niche situation and would be difficult to exploit.