ΔE 12.1, fair: the same colour family, but not a straight swap. IJA Grey Green is a little lighter, more muted, cooler than Skeleton Legion.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). IJA Grey Green is a little lighter, more muted, cooler than Skeleton Legion.
The same difference applies the other way round: Skeleton Legion is a little darker, 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 Skeleton Legion on the colour wheel See IJA Grey Green on the colour wheel
All matches: Skeleton Legion equivalents · IJA Grey Green equivalents