Ditto for the asbestos --- if it's not in a state where fibers of it can easily flake off and float around to be inhaled (technical term is "friable"), it won't do any harm.
The EPA, for one.
https://www.epa.gov/asbestos/protect-your-family-exposures-a...
The problem is inhalation of fibers, so if the fibers are not in the air and inhalable, they pose no risk.
Don't ever trust anything a real estate agent tells you, especially if that agent stands to gain financially from your actions; they are the "used car salesmen" for houses. They lie.
>only one case did another ever admit to knowing of a problem where signing off on the proper lead paint/radon/asbestos warnings.
A problem? Like the existence of them? You should test for radon before buying a house, so you'll know. I have friends who turned down a house with high levels of radon because the seller wasn't willing to negotiate for radon remediation. Lead paint isn't a concern as long as it is undisturbed, however, you need to treat every house built before 1980 as having lead paint. Asbestos? I have asbestos in my house, which was disclosed to me, but it was professionally wrapped, so safe as long as it remains so. Pretty much every house that's as old as mine contains asbestos, at least in my neighborhood. So it doesn't effect the value of it at all, as long as it's wrapped.
Same goes for old ceiling panels, often loaded with friable asbestos. An act as simple as drilling a hole, or installing new can lights can load up the room with airborne fibers if done carelessly.