No need to go overboard. You are round-abouts 100km from my place, with roughly the same weather conditions. A cellar probably has more humidity than my office though.
Fresh rolls are not neccessarily dryed after manufacturing which may even involve water cooling. So do not expect fresh rolls to be dry. A standard filament dryer usually does the job for me. No need to go over board in our neck of the woods unless you are looking at engineering filaments.
As for the root cause of that high humidity, I really would not blame your wife. The AMS does a terrific job of keeping its insides dry for a while if it is closed and well stocked with fresh dessiccant. Otherwise, it only serves half its function.
Have a look here as to a set-up operating very well not too far from you. It also includes a link to the Bambu Filament Drying recommendations.