I think the additional rows might be reserved/used for custom colours, so there might be colours already in them but disorganised or incomplete.

A few characters with custom skintones reference "row 31" of the table (out of 24 we can access), though I haven't seen anything inbetween, so it seems like they'd have some to spare. Whether they're willing to open them up is a different question, and more about their vision for the characters than what players could want to do with it.