ΔE 13.8, fair: the same colour family, but not a straight swap. Military Yellow is a little darker, more muted, cooler than Cokum Copper.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Military Yellow is a little darker, more muted, cooler than Cokum Copper.
The same difference applies the other way round: Cokum Copper is a little lighter, more saturated, warmer.
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 Cokum Copper on the colour wheel See Military Yellow on the colour wheel
All matches: Cokum Copper equivalents · Military Yellow equivalents