ΔE 13.5, fair: the same colour family, but not a straight swap. Royal Blue is noticeably lighter, cooler than Shalaxi Violet.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Royal Blue is noticeably lighter, cooler than Shalaxi Violet.
The same difference applies the other way round: Shalaxi Violet is noticeably darker, 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 Shalaxi Violet on the colour wheel See Royal Blue on the colour wheel
All matches: Shalaxi Violet equivalents · Royal Blue equivalents