I wouldnt bother with fungicide..
with the pots all opened up, not bagged, you shouldnt have any fungus growth at all..
plus fungicide is pretty toxic..to people and pets..not a good thing to be spreading around indoors..
I highly doubt you will need it at all..I would just forget about it completely.
I seal my plants up in plastic bags all winter, and I dont even use or need fungicide!
sounds like your dormancy system is pretty good!
should work fine..
the only thing I would worry about with an "indoor dormancy" is the plants being too warm..
but if its truly an unheated room, and it generally stays in the 30's or 40's all of the time,
then that is pretty ideal..
if its a room you live in though, and you heat it up at times in the winter, thats not so good..
think of the room as a big refrigerator!
if it truly feels like a refrigerator all winter, then you are in good shape..