ΔE 14.9, fair: the same colour family, but not a straight swap. Old Copper is noticeably darker than Sycorax Bronze.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Old Copper is noticeably darker than Sycorax Bronze.
The same difference applies the other way round: Sycorax Bronze is noticeably lighter.
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 Old Copper on the colour wheel
All matches: Sycorax Bronze equivalents · Old Copper equivalents