CSL possible pull back to low $200's, page-51

Currency hedging only provides a once off somewhat insurance-like payment when exchange rates move adversely.

Any long term re-rating of the AUD will only be covered by currency hedging for the short term, so hedging won't save the CSL price in the scenario outlined by the OP.

Since CSL effectively operate in USD any upward or downward change in AUD will not have any impact on PPE and acquisitions planning, except in Australia, which in the scenario outlined by the OP, would have a negative effect (although insignificant given Australia's small overall representation of CSL's total market).