.
In Finland we cannot use fondant i winter because bees need water to dilute it.
.
I can understand that the extreme cold might be an issue for you with that, but fondant is 82% approx sugars, and 18% water, very similar to honey itself.
In OUR climate in winter the rising heat from the cluster cndenses on the face of the fondant, and the bees eat it from there. In Denmark fondant is primarily a summer food, to keep the bees interested in dearths.
We rarely feed fondant, and have not needed it for four years now, as we find our autumn feed is sufficient to see the bees through till March at least, and many require no feeding until autumn again. Again, the idea you have that we are all into our bees feeding them in the dead of winter is inaccurate, although understandable if you go by the traffic on this forum.
However, when you DO have to feed fondant, you place the lump (maybe 3 or 4Kg, smaller lots are a waste of time and a source of dangerous winter disturbance) inside a polythene bag, and slash one side of it removing a strip of the plastic to expose the fondant inside, then lay this cut strip across the top bars immediately above the bees (not above a feedhole, just directly down onto the topbars). The warm moist air from the cluster enters void as the bees eat it out and this itself is all the water they need.
Bees wintered on nothing but fondant seem to do just about as well as those on nothing but stored syrup. Thus a beekeeper can make their personal choice with no fear that their choice is wrong, just different.