ΔE 12.0, fair: the same colour family, but not a straight swap. Iridescent Copper Light (Coarse) is noticeably lighter than Sycorax Bronze. They are different kinds of paint: Citadel Sycorax Bronze is a metallic and Golden Iridescent Copper Light (Coarse) is a pearl paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Iridescent Copper Light (Coarse) is noticeably lighter than Sycorax Bronze. They are different kinds of paint.
The same difference applies the other way round: Sycorax Bronze is noticeably darker.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Sycorax Bronze on the colour wheel See Iridescent Copper Light (Coarse) on the colour wheel
All matches: Sycorax Bronze equivalents · Iridescent Copper Light (Coarse) equivalents