Figured-bass numerals render in a plain upright style distinct from both the dynamics style and the expression style

Figured bass numerals are set upright (never italic) and in normal weight (never bold), visually distinct from both dynamics (bold italic) and expression text (italic).

Gould; Read (figures set in plain upright numerals, distinct from italic expression text).

This rule is about where marks land on the page, so it can only be judged after engraving. Collision and spacing faults live here.