ΔE 10.7, fair: the same colour family, but not a straight swap. Barbarian Skin is a little darker, warmer than Buff.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Barbarian Skin is a little darker, warmer than Buff.
The same difference applies the other way round: Buff is a little lighter, 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 Buff on the colour wheel See Barbarian Skin on the colour wheel
All matches: Buff equivalents · Barbarian Skin equivalents