As a former attorney for the chief counsel of the I.R.S. who specialized in nonprofit organizations, I believe Mr. Trump is also criminally liable for his actions. If I were still at the I.R.S., based on the lawsuit, I would make a criminal referral, on charges of tax evasion or false statements on a tax return, or both.
On the tax evasion charge, the government must demonstrate that the defendant willfully failed to pay a tax he owed and acted to disguise or attempted to disguise that evasion. For a false statement charge, the government must show the defendant willingly signed a return under penalties of perjury, making a materially false statement that he knew was false.
These are not easy charges to prove, but the Trump Foundation is a nonprofit organization that is entrusted with money to be used exclusively for public charitable purposes. Any use of foundation money to benefit himself is akin to theft.