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