The 6 and 9 characters are somewhat ambigous on the wheel.

[roconnor-blockstream]

• One idea is to place the characters above the arrow on the wheel to help disambiguate them. Or put the characters under the box with an upward arrow.
• A more forceful solution is to change fonts for the 9 character.

[apoelstra]

It actually probably wouldn't be too hard to change centreshow to underline those two specific characters