I know, she can, and has, partnered with the county AG to bring a criminal case against Trump org. She could do the same against Trump himself if she thought she could meet the higher standard of proof. Apparently, she doesn't believe she can prove a crime.
Banks are responsible for their own assessment; they don't automatically accept whatever valuation you negotiate with the tax assessor. And BTW, around here tax assessments are reviewed only every 5 years. Valuations can change a lot in 5 years.