ᐅ Severe Mold Infestation in a House Sold Through a Forced Auction

Hello house building forum,
My parents recently had a house sold under foreclosure. Unfortunately, we were unable to inspect the house beforehand, so we didn’t know what to expect:
The walls along the chimney are completely covered with mold. The contractors covered the walls with drywall and then plastered over it. The problem: the mold still came through.
I’m afraid my parents made a mistake by trusting the contractors.
Does anyone have experience with this and can suggest what should be done in the current situation? Can the covered-up mold become dangerous? Both for the house and for our health?
I would appreciate your opinions. Pictures are attached.
The first three are from before and the last one is from after.
Thanks in advance!

Oh no, the pictures look bad. Was there no property listing before the foreclosure auction?

In any case, the shafts appear heavily water-damaged, not necessarily moldy. Has anything been done to address the water infiltration, such as installing new stainless steel pipes, sealing, or similar measures?

I would tackle severe discoloration and mold by using a chipping hammer to remove the plaster generously. Afterwards, apply plenty of mold remover and rebuild. Of course, this only helps if you have already eliminated the cause of the mold.

Unfortunately, no. The original owners didn’t allow anyone into the house. After the purchase, we understood why :P Naturally, that also meant the price was very low.
Yes, it has already been sealed. No more water is getting in.
So, ideally, should the new walls be removed and the decayed walls treated?
What could happen in the worst case if nothing is done?

I’m not sure about that... I would definitely consult a professional.

Personally, knowing that it looks like that beneath the drywall would not give me peace of mind, regardless of whether it is safe from a health perspective.

How does one even come up with the idea of simply covering such rotten walls with drywall? Following the motto, "out of sight, out of mind"? Crazy.

Looks like a rotted chimney. Get a professional chimney builder to install a stainless steel liner. After that, use a drying device to dehumidify the walls.