ΔE 13.6, fair: the same colour family, but not a straight swap. Kossite Flesh Wash is noticeably lighter, cooler than Warm Skin Tone.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Kossite Flesh Wash is noticeably lighter, cooler than Warm Skin Tone.
The same difference applies the other way round: Warm Skin Tone is noticeably darker, 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 Warm Skin Tone on the colour wheel See Kossite Flesh Wash on the colour wheel
All matches: Warm Skin Tone equivalents · Kossite Flesh Wash equivalents