LAH_

To me adding coolant to the system means there is a leak somewhere. It's a closed system so it has to go somewhere to disappear from the reservoir. Measuring in millimeters could be deceiving since the level changes with system pressure and temperature. Having said that, I had my coolant below min at one point, consulting my indy did not even initiate a pressure check. I ended up topping up and observing how it goes but haven't fallen below min since then. Go figure... I don't know how this could be. But the system is quite complex. Maybe there was a leak and it was blocked by something I really don't know. In the end, if there is no symptom, there's nothing to fix. If my coolant goes low again, I will top it up and observe. If persistent and disappears quickly then I would ask for a leak check.

Rcsac

My coolant level is in the same place, it hasn't dropped even a millimeter, I'm saying that by looking at it with the naked eye.
I'm just surprised that I can still smell the burning coolant when I parking the car and when I get out of the car. I don't think I feel it every time like before I changed the radiator and I think I felt it less. If I open the hood while the engine is running, I can clearly smell the burning coolant. I believe that it is a complex system as you said.
I'm going on annual vacation for a couple of days, so I'll see if the spilled coolant evaporates as the garage says on the open road after 3000km, or if some crap or change will happen. If there is no change and I still feel the smell, I will go to the garage again. Maybe I will go to another garage during the annual vacation for a check.
Thanks for you time