Criterion 26 requires the use of data, but does the ACCME require that accredited providers use identifiable patient health or practice data?

No!  The use of identifiable patient health or practice data is not required or expected of providers by the ACCME.  In fact, the ACCME recommends: “Providers should seek appropriate guidance from institutional policies and practices concerning the protection of confidential and identifiable information when including health or practice data in CME activities.”