ΔE 13.6, fair: the same colour family, but not a straight swap. Brown RLM26 is more saturated, cooler than Black Rose Immortal.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Brown RLM26 is more saturated, cooler than Black Rose Immortal.
The same difference applies the other way round: Black Rose Immortal is 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 Black Rose Immortal on the colour wheel See Brown RLM26 on the colour wheel
All matches: Black Rose Immortal equivalents · Brown RLM26 equivalents