ΔE 12.6, fair: the same colour family, but not a straight swap. Old Rose is a little lighter, warmer than Elder Flower.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Old Rose is a little lighter, warmer than Elder Flower.
The same difference applies the other way round: Elder Flower is a little darker, 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 Elder Flower on the colour wheel See Old Rose on the colour wheel
All matches: Elder Flower equivalents · Old Rose equivalents