An intentional misrepresentation of a material fact in a rental agreement or application may not be remedied or cured.

Is there anyway to remedy this quickly?

I don't do airbnb, but from what i have heard, short term tenants will tend to be either easy on your place or really hard on it, your neighbors probably won't be happy about it, your whole model could be shut down at any moment because of the HOA, so there's plenty of expenses involved in remedying any of those issues3. you should consider reading the AirBNB terms of service, as I believe it specifies the insurance requirements, along with consulting your mortgage holder4. 

They will cause constant issues like clogs, electrical shortages, lead citations, remediation if there is asbestos in piping or building materials, etc.Maintenance and CapEx are your two most variable expenses.

Does anyone have recommendations for a cheaper remedy ?

Would the remediation affect the top unit that has no mold or problems at all?

Found what was wrong with the property during inspection, had multiple contractors quote remedies, and leveraged it to a large credit at closing that paid for the down payment and a check to us!

Your best bet for mold is to get a mold remediation company out to deal with it.

There could be other unseen environmental risks that the old phase 2 did not remediate or something affecting the area since 2012.

You suffered a loss to your property, they need to pay to remediate.