I personally think all Mfgs should be spanked for NOT labeling all switches, but that may be
I am not familiar with that model / floorplan, but I do recall looking at a unit that had what I thought was an extra switch in main bath with shower. It turned out that the switch was an additional switch to turn on/off the water pump. i.e you are in shower and realize water is off; you don't have to get dressed to go outside to turn it on. Similar would apply is you needed to flush and oops no water