ΔE 11.7, fair: the same colour family, but not a straight swap. Forest Faun is a little darker, cooler than Rotten Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Forest Faun is a little darker, cooler than Rotten Green.
The same difference applies the other way round: Rotten Green is a little lighter, 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 Rotten Green on the colour wheel See Forest Faun on the colour wheel
All matches: Rotten Green equivalents · Forest Faun equivalents