ΔE 13.6, fair: the same colour family, but not a straight swap. Kossite Flesh Wash is noticeably lighter, cooler than Warm Skin Shade.
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 Shade.
The same difference applies the other way round: Warm Skin Shade 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 Shade on the colour wheel See Kossite Flesh Wash on the colour wheel
All matches: Warm Skin Shade equivalents · Kossite Flesh Wash equivalents