ΔE 13.7, fair: the same colour family, but not a straight swap. Tan (USAF) is a little darker, more muted than Kislev Flesh.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Tan (USAF) is a little darker, more muted than Kislev Flesh.
The same difference applies the other way round: Kislev Flesh is a little lighter, more saturated.
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 Kislev Flesh on the colour wheel See Tan (USAF) on the colour wheel
All matches: Kislev Flesh equivalents · Tan (USAF) equivalents