My first thought was "I want to design a pair of twins". My second thought was "Since the moon is already a huge plot point in the story, I should make them Sun and Moon themed" (hence their names).

Their clothes were designed to embrace their cute looks as children (since they realize at one point that as much as they despise their child forms, acting like an adorable, clueless kid makes most things a lot less troublesome to deal with) while still retaining their sun and moon theme.

A big factor in their overall design was just my curiosity to be honest "Everyone learned what they know from somebody at some point" and "Snow and White are the ones who are always looked at in blame of raising Figaro and Oz the way they did and in turn causing a lot of problems in history, but what if they weren't completely to blame?" and so, why not put together a pair of twins who had taught Snow and White? Teachers who played a great role in molding them into the people they are today.
(I also kinda just wanted them to be in Figaro and Oz's positions for once lol)

What do they think about the way Figaro and Oz were raised? Quite frankly they had little idea they even existed for a Very long time. They would keep tabs on Snow and White just enough to know that they were still alive and kicking...for the most part (I'm so sorry White-). When they do really find out about them is when they meet After Amia (their current student) is summoned as a sage's wizard and to be fair they genuinely don't care That much? What Snow and White do with their students is frankly none of their concern and considering that they're probably 90% of the reason Snow and White raised Figaro and Oz that way to begin with their methods are likely things they themselves practice and naturally quite normal to them.

(This turned out a lot longer than I thought skghk my apologies I just like talking about my wizards children)