ΔE 10.8, fair: the same colour family, but not a straight swap. Dark Red is a little darker, more saturated, cooler than Light Umber.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Dark Red is a little darker, more saturated, cooler than Light Umber.
The same difference applies the other way round: Light Umber is a little lighter, more muted, 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.
See Light Umber on the colour wheel See Dark Red on the colour wheel
All matches: Light Umber equivalents · Dark Red equivalents