ΔE 27.9, loose: different enough that you should pick on purpose. Twilight at Gettysburg is noticeably lighter, much more saturated, cooler than Hexed Violet.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Twilight at Gettysburg is noticeably lighter, much more saturated, cooler than Hexed Violet.
The same difference applies the other way round: Hexed Violet is noticeably darker, much 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 Hexed Violet on the colour wheel See Twilight at Gettysburg on the colour wheel
All matches: Hexed Violet equivalents · Twilight at Gettysburg equivalents