Tainted Gold vs Gladius Bronze

How close are they?

ΔE 26.1, loose: different enough that you should pick on purpose. Gladius Bronze is noticeably lighter, warmer than Tainted Gold.

Can I use Gladius Bronze instead of Tainted Gold?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Gladius Bronze is noticeably lighter, warmer than Tainted Gold.

Can I use Tainted Gold instead of Gladius Bronze?

The same difference applies the other way round: Tainted Gold is noticeably 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.