The answer given in Cranial Insertion (
here, for anyone who might yet be unfamiliar with this excellent resource) is correct: Anita doesn't return anything to her hand, but will discard a card.
Dispersal instructs Anita to return “a nonland permanent they control with the highest converted mana cost among permanents they control” to hand, but
Gold-Forge Garrison means the highest converted mana cost among Anita's permanents is 4, but it's a land, so it can't be returned, and Anita doesn't control any non-land permanents with converted mana cost 4, so nothing else can be returned either.
In general, contacting Wizards Customer Service for answers to anything beyond the simplest rules questions has historically been unreliable at best–the folks there are trained in customer service, not game rules, so when they answer a rules question it's often only as reliable as the personal rules savviness of whichever CS rep happened to be the one to answer that specific email.
Edited Callum Milne (Jan. 16, 2019 02:54:07 PM)