Flayed One Flesh vs Rosy Highlight

How close are they?

ΔE 8.4, close: similar, with a visible difference side by side. Rosy Highlight is cooler than Flayed One Flesh.

Can I use Rosy Highlight instead of Flayed One Flesh?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Rosy Highlight is cooler than Flayed One Flesh.

Can I use Flayed One Flesh instead of Rosy Highlight?

The same difference applies the other way round: Flayed One Flesh is 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.