Can a lawyer be disciplined for not maintaining proper financial records?

The answer is yes. Under Rule of Professional Conduct 8.1(b), a lawyer can be disciplined for knowingly failing to respond to a demand for information from a disciplinary authority. Obviously, this rule is subject to the Fifth Amendment of the U.S. Constitution and Article 1, Section 9, of the Pennsylvania Constitution. But the lawyer does have an obligation in disciplinary proceedings to produce information that is not protected by the Fifth Amendment and/or protected by attorney-client privilege.