I do agree that I’m sad to not see assertive and politically savvy Tiara but that was before she got her memories from 20th century Japan. I find her insecurities to be really sympathetic because it’s one thing to stick to the etiquette rules from your current period, but when you remember a different set of beliefs from another time period that overrides what you previously believed, it’s hard to not get confused and anxious.
Also, the plot with the Marine Forest kingdom happened so who is the say the sea kingdom’s plot won’t? At least, that’s how I would’ve felt if I was in Tiara’s shoes and remembered my 20th century memories that late in the game