We have a clause in our lease that plumbing clogs not caused by mechanical/material defects in the plumbing will be charged to the tenant, and if your lease doesn't have similar I would recommend such a clause.

Who deals with any mis-measurement issues or defects?

This property had a few defects which I used to negotiate down. 

We have a lease clause that plumbing issues caused by the tenant that are not the result of a mechanical or material defect in the plumbing material are billed to the tenant.

He sued claiming the stair was defective, even though he told his neighbor he just wasn't paying attention and missed the step.

The Seller is required to disclose any material defects and a fire would definitely fall into that category. 

Does it have material defects such as a roof, foundation, heating system issue etc?

Also, you don’t say what he did wrong and what you did to bring the defects to his attention so he can correct them.

If the failure to join was a ministerial oversight, then a new deed would probably cure the defect. 

Since they notified you of this, you should get it taken care of as your insurance may not cover a claim if there is an accident because it was a known defect.