How to treat damp masonry

Hello everyone, I had some difficulty finding a suitable forum for our problem. Unfortunately, we are (not yet) homeowners and therefore rent our place. I hope to find willing responders here nonetheless ;). Now we have noticed increasing dark spots under the white wallpaper in the bathroom and have informed the landlord. He came, measured the wall moisture, which was damp at the spot where the spots are and also at the section that is the exterior wall area. Now roofers came who found that water was running down the exterior wall from a downpipe and presumably was seeping in where the pipe clamps are embedded in the masonry. The guys then relocated the pipe. But now the problem: my lack of expertise in this area. The landlord now says we should wait for the time being; the wall will dry by itself, and the cold and frost would even drive the moisture out of the wall faster than, for example, warm weather. In one or two weeks we are supposed to do a comparison to see if the spots have gotten bigger or stayed the same, since it could still have been caused by us. My follow-up question was whether it really makes sense to just wait instead of taking appropriate measures to dry it faster. Especially since the dark spots, so far under the wallpaper, are probably mold. Things like a dehumidifier were suggested, but only as possibilities, with no willingness to take action themselves. I am of the opinion that if I pay rent for an apartment, the landlord is responsible for such matters. Of course, provided that the cause is not the tenant, so us. Naturally, it is also possible that we are the cause of the mold, although then the spots would probably be on, and not under, the wallpaper (far from a wallpaper seam gap). However, we have lived here for two years and have not changed our ventilation behavior, so mold would probably have formed. Is it now the correct procedure to wait two weeks first, instead of drying the wall promptly?!

Spontaneously, I would first say to ventilate thoroughly and set up dehumidifiers. The latter are available in different variants (electric or with granulate blocks). In your case, I would take an electric one, they have a bit more power (you can also rent them at hardware stores).