Ann: Heron commences drilling program at Currawang, page-13

Minimal

AUD/USD 0.79 v's Feas. 0.71 (and probably the main reason for the Zn price being up in USD).
Redbeard did those checks/adjustments and across Zn, Cu, Au & Ag it made little difference.
BTW: Cu in the feas. was $3.00 US (at AUD/USD =. 71). Current Cu price approx. USD $2.88

I'm happy you starting to look at the variables and their effect you should come to the same conclusion.
(Apart form when you effectively wrote it was a lot of crap).

Those prices and currency values are on page 426 of the DFS. (In the pressos too in very small print).