In case anyone cares, I came up with a few imperial kimono rules/traditions, but decided to make it more simple than I originally wanted:
1. Red + Indigo is reserved highest class families (kurai-ichi).
2. Younger sims will normally use stronger colors/patterns than elders.
3. The "tuft" meaning marriage, so unmarried sims will not use those versions.
4. Also, regular households stick to the earth colored shoes (forgot their name), while younger/modern members of upper class families more often choose a colored version (in my culture there are 7 "protected families" seen as upper class, not necessarily due to wealth).