Bank will verify income, employment, credit history, and order an appraisal.

It sounds like you want to add an ADU so you will need two electrical meters, the floor between the units will need to be fire rated, verify existing water meter/service is the correct size, lot occupancy and a few more items that need to be well thought out.

You should verify they are still there.

I say pseudo collateral because the collateral is not encumbered, but just verified to set your line limit. 

Have you verified it with a local property manager or with Rentometer?

This is at the underwriters discretion so verifying with your lender ahead of time would be ideal. 

At the very minimum you'll want to verify that the QI is structuring the exchange according to the safe harbor in Rev Proc 2000-37 and provides an exchange agreement that verifies that. 

Regardless, you should still screen them like any other applicant and ensure and verify that they have an income source like any other applicant... because like many have mentioned, what happens on month 13?

So I cannot verify the integrity of their work.

I would give them no more than three days and call the utility company to verify.