A colorblind player will not provide you feedback about features on your world that depends on color, because they don't know that your world depends on color in the first place.
During testing, you need to find and reach out directly to colorblind players, point out to them, and discuss exactly the features of your world that depend on color in order to improve the accessibility of your world.
When you are not colorblind, you need to have awareness of cases where color becomes an issue in order to notice and ask the right questions.
See: https://www.youtube.com/watch?v=KbFs9ghIIEI Solving an Invisible Problem: Designing for Color-Blindness in Games by Douglas Pennant (a game developer who is colorblind)
See: https://www.youtube.com/watch?v=KbFs9ghIIEI&t=1640s
Japanese fonts have different styles, just like English fonts.
Players have opinions about default fonts.
Consider asking your localizer for advice about which font to use that matches your world. This is likely true for other languages.
You can find fonts on Google Fonts.
See: https://fonts.google.com/?subset=japanese
See: https://twitter.com/cannorin_vrc/status/1465732203347083264