RMA Gain/Loss not hitting original COGS account

Summary:

Under average costing, COGS accounts are derived through mapping sets for Product, Cost Center and Channel, which read the invoice flexfields.

RMAs must reverse exactly the account combination hit at COGS, but no invoice or credit memo is created for RMAs, so those flexfields don’t exist when the RMA is accounted.

EFFs are on Sales Order of RMA but there is no even class for Sales Orders in mapping sets.

Sales order EFFs such as Channel, product, cost center also aren’t available as mapping set sources for this event class, so today the RMA posts to fixed RMA Gain Loss accounts instead of the original COGS account.