ΔE 16.1, loose: different enough that you should pick on purpose. Fyreslayer Flesh is a little lighter, more muted than Hardened Leather.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Fyreslayer Flesh is a little lighter, more muted than Hardened Leather.
The same difference applies the other way round: Hardened Leather is a little darker, 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 Hardened Leather on the colour wheel See Fyreslayer Flesh on the colour wheel
All matches: Hardened Leather equivalents · Fyreslayer Flesh equivalents