ΔE 14.7, fair: the same colour family, but not a straight swap. Indigo Sky is noticeably lighter, more muted, warmer than Macragge Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Indigo Sky is noticeably lighter, more muted, warmer than Macragge Blue.
The same difference applies the other way round: Macragge Blue is noticeably darker, more saturated, 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 Macragge Blue on the colour wheel See Indigo Sky on the colour wheel
All matches: Macragge Blue equivalents · Indigo Sky equivalents