ΔE 29.8, loose: different enough that you should pick on purpose. Light Magenta is a little lighter, more saturated, warmer than Dechala Lilac. They are different kinds of paint: Citadel Dechala Lilac is an opaque base/layer paint and Golden Light Magenta is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Light Magenta is a little lighter, more saturated, warmer than Dechala Lilac. They are different kinds of paint.
The same difference applies the other way round: Dechala Lilac is a little darker, 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 Dechala Lilac on the colour wheel See Light Magenta on the colour wheel
All matches: Dechala Lilac equivalents · Light Magenta equivalents