You can extend communitycommons.ORM.getValueOfPath with an extra argument (the date format string) and and extra if case (menber instanceof MendixDateTime) and then apply the dateformat. I think it requires only basic java skills to add that case.
Otherwise, file a feature request and I will add it in the next release.
Solved in the 2.1(.1) release in the appstore.
This seems to be in the core (substituteTemplate calls getConstantValue) thus fixing Java does not work. The only way around seems to be to replace the Date field in the template with a string field and add an extra attribute to your entity representing the DateTime as String. Update this string field in a before commit event.