Mold Remediation question

Overheating alone would leave the air bone-dry, so no mold, just nosebleeds, headaches and nonstop colds. I'm guessing that said tenant then over-humidified the overheated apartment, resulting in heavy condensation, and thus mold.

In any event, in coops any leaks from exterior walls or from in-wall plumbing would be their responsibility, and their insurance would generally cover damage to your apartment and belongings.

That explanation sounds odd. There would have to be moisture in the air (presumably from a leak) for mold to form. Temperature alone wouldn't be enough to create the level of severity you describe.

I would definitely consult an environmental remediation specialist and include language in your contract about seller and management's knowledge of the situation so that you have all the information available. Would they ever provide you with the original reports from the incident?

I would really be careful and suggest getting your own inspection for peace of mind.
Our previous apartment had ongoing problems even though the owner repeatedly tried to argue that it was - oh - because of all sorts of BS including 1. my houseplant (I had one orchid) 2. our books 3. an old leak from years before that had since been fixed (not true at all - it leaked badly throughout our entire stay there 4. mold was now dead and couldn't hurt anything when it was dry and on and on. Plenty of health issues and aggro - get it checked.