WWI German Mauve vs Cold Flesh

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. Cold Flesh is a little lighter, more muted than WWI German Mauve.

Can I use Cold Flesh instead of WWI German Mauve?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Cold Flesh is a little lighter, more muted than WWI German Mauve.

Can I use WWI German Mauve instead of Cold Flesh?

The same difference applies the other way round: WWI German Mauve 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.