Our office manager argued that all the proposed repair such as drywall, floor, paints, doors, windows, thermal and moisture protection treatment, etc are part of the tenant responsibility.

If the ADU you're proposing is the make-or-break between this deal penciling out or not, AND if it is pivotal for your plans that it be the height that you are planning, I would personally advise you to abandon this deal. 

Does anyone know if a non-veteran buyer can assume a VA loan with the intention to rent the proposed?

Apparently there are quite a few women who feel a need for the group you proposed, but in my opinion it is counter productive.

This means you close your purchase and pray the appraisal with the proposed ADU has the value you think.

I'm not an attorney so please consult one in your state to make your decisions.You could propose they master lease the property as a trial period BEFORE you agree to purchase terms which would transfer title. 

Kevin, I actually proposed your solution but the seller need a quicker close so I just made it happen.

That's one conversation.Since the situation is out of both of your control, I would propose full credit for the days between incident and scheduling with the city, and split city scheduling delay days 50/50.

You really shouldn't propose anything until you have a conversation and understand what the financial needs or expectations of the seller are in advance.

Some DSCR lenders will allow the proposed income to qualify, but needs to be able to pass an appraisal.