A few towels or some large microfiber clothes could sort it out, to a point where using the heater could make it better. Think it could just be a case of letting the conditions inside the car just get to far and not using the heater only makes them worse and worse.
I have something similar to what you suggest in my car, it has some coloured beads in it when they change colour, you then take it out and put it in the microware and wait till it cools and put it back in the car.
I guess one could be in the car longer if you doing lower speeds or sitting stationary alot or parked up waiting and from my experience with having full cars a lot it really depends on the conditions and the usage.
Even now i still get a build up on the inside of all the windows and regularly wipe them down and then again with another dry cloth and a 3rd if need be.
We can only go by what windy tells us and the picture might not show drops on the screen but due to the angle of the pic of the sun roof you can see them on it but not on the screen and often if they was they’d be running down the screen.
it’s all about solution’s and deffo not about being right or wrong.
Also sometimes lots of wet feet and clothing don’t help either. Which is often the case with my kids.
Also it’s a big space that could retain alot of moisture, sometimes my windows ain’t foggy but get very wet on the inside and i have the heater and (sometimes a/c) on pretty much all the time. Turn it off or down to low for a bit and the wet comes back.
Either way something needs doing as if it’s on the screen for example and windows it will only flow one way down via the path of least resistance and maybe get into the electric’s and thats not good.
Drying it all off well and if the mats are wet take them out and inside the house to dry them fully, if the carpets are really wet a hairdryer could help, on a dry day of course and/or run the cars heater for a bit with windows open a little and if it still happens then maybe it’s a seal somewhere letting in the water and that would explain if it’s raining or you been driving in the rain and it happens more than usual.
If it comes from sunroof area it could indeed be that but it could also be any seal even a floor one. it’s why i asked is the floor wet as well and in any particular place more than others. Generally the materials will retain water like if the car didn’t have a sun roof (like ours) has never had drops like that on the roof a sit’s all material, but it will show up on the glasss surfaces and a good coating of it is needed until droplets do form.
I don’t let it get to that stage, So i do think before windy takes it to the dealers regarding the moisture build up they should try and get as much water out of the car as possible and as regular as possible if needed and see. Maybe try and use the heater more often also, when possible but with such a short range in winter conditions, might not be easy or ideal. Also try not to leave anything wet in the car, take it out, especally those wet cloths you use.