For ERISA-governed plans, DoL FAB 2003-3 (May 19, 2003) allows plans to charge an individual plan account in a DC plan for administrative expenses pertaining solely to that account. That includes charging either the EE's or the ex-spouse's account for the costs of reviewing and processing a QDRO.

Treas Reg § 1.457-10(c) engrafts the QDRO rules of IRC § 414(p) into the 457b plan context.

However, I am unable to find anything that would permit a 457b plan to charge the employee or ex-spouse for reviewing and processing a QDRO. As ERISA is not at play to preempt state trust law, I'm wondering if anyone has run across this issue and concluded anything other than if the charge is reasonable, state trust law permits it to be charged against and paid out of the 457b plan trust.

At least one state statute expressly mentions payment of fees relating to QDROs under government plans, and is not consistent with your speculation about the standard. I did not check to see if 457(b) plans in particular are covered.