So I took her in to the dealership this morning. First they told me that they had no loaners for me (and that they couldn’t loan an Acura to a Subaru driver), and that Enterprise wouldn’t be open until 0730. Then they only took about 45 minutes with the car, during which time they told me that one of the new clamps was slightly loose, and they tightened it up. They told me what I was probably smelling was the burn-off of excess spillage from when the lines burst or when they re-filled the radiator at the place in Chicago. Per the mechanic, there’s no evidence of any leaking from the head gasket.
By the time I got near work this morning, I could smell the burning coolant again, and some sort of “hot plastic” (not burning plastic) smell from the vents. I ran it through the car wash and had the underbody wash done as part of it. As soon as I did that, the coolant smell went away.
We’ll see how this plays out.