ΔE 14.4, fair: the same colour family, but not a straight swap. Light Umber is noticeably darker, cooler than Sylvaneth Bark.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Light Umber is noticeably darker, cooler than Sylvaneth Bark.
The same difference applies the other way round: Sylvaneth Bark is noticeably lighter, 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 Sylvaneth Bark on the colour wheel See Light Umber on the colour wheel
All matches: Sylvaneth Bark equivalents · Light Umber equivalents