Does mold go away by insulation or not?

Does it make sense not only to ventilate in bursts but also to tilt the windows in two rooms to create a draft? Of course, this would only happen when we are not at home, e.g., while we are working.

The danger then is that really cold zones form around the windows and moisture accumulates there, causing mold. The warmth inside the house is an important factor in "dry ventilation." More effective in preventing mold is usually the combination of opening windows wide for a few minutes/ventilating in bursts and heating more generously overall. And this is especially effective for getting moisture out of the house when it is significantly colder outside (even if the heating costs in an old building sting a bit). So even if the instinct right now is "we want to keep the warmth inside the house," when it comes to getting rid of moisture, this is exactly the right time for "dry ventilation." (By the way, this is also done in new buildings, which often still have a lot of moisture in the walls/screed/etc.) There is a reason why people speak of "dry heating air" in winter here. You now have a hygrometer, so if you look at it when you open the windows wide, you can actually watch the humidity drop.