ΔE 14.8, fair: the same colour family, but not a straight swap. Midnight Purple is noticeably darker, more saturated, warmer than Terrestrial Titan.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Midnight Purple is noticeably darker, more saturated, warmer than Terrestrial Titan.
The same difference applies the other way round: Terrestrial Titan is noticeably lighter, more muted, cooler.
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 Terrestrial Titan on the colour wheel See Midnight Purple on the colour wheel
All matches: Terrestrial Titan equivalents · Midnight Purple equivalents