ΔE 14.4, fair: the same colour family, but not a straight swap. Dwarven Gold is a little lighter, cooler than Castellax Bronze.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Dwarven Gold is a little lighter, cooler than Castellax Bronze.
The same difference applies the other way round: Castellax Bronze is a little 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 Castellax Bronze on the colour wheel See Dwarven Gold on the colour wheel
All matches: Castellax Bronze equivalents · Dwarven Gold equivalents