ΔE 11.1, fair: the same colour family, but not a straight swap. Green Hell is a little darker, more saturated, warmer than Medieval Forest.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Green Hell is a little darker, more saturated, warmer than Medieval Forest.
The same difference applies the other way round: Medieval Forest is a little lighter, more muted, cooler.
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 Medieval Forest on the colour wheel See Green Hell on the colour wheel
All matches: Medieval Forest equivalents · Green Hell equivalents