My relationship to the personalities of the 3 PCs is indifferent, they have different traits and are discernible but stay within an archetype (The Grumpy Officer, The Superficial Flirt, The Methodical Thinker) without rough edges or greater surprises.
So far I stumbled over two outliers: The crippling of Tomas by Thalia (but then the eye-for-an-eye justice is a common trope in western fantasy) and Kira's ignorance of the OutOfFoodException (what does it cost in a medieval setting to feed 3 persons for a day? is it more than a huge jug of beer in a tavern?). In a way those outliers make characters more interesting, but I am not sure if it's intended that the more extreme traits are both at the negative end of the scale... The inability to select the food problem as topic makes Kira an arsehole in my eyes (not that I as player would exclusively choose this option, it's the expectation that Kira as character for sure thinks about the hunger issue and can address it) and Joanne will not heal her anymore.
I think the issue is you're seeing them in these three archetypes which you have posited and they're not really like that at all. Kira isn't particularly grumpy (Despite Thalia's jokes) but is often insecure, especially when she gets closer to people. She's also insecure about her intelligence because she's been bullied about it before even though she's not stupid and is in actual fact quite smart. Joanne is a control freak so you're not far off methodical but it's far more nuanced than that. It's not something you've brought up specific comments about, though, so I'll leave it at that.
As for Thalia, she's a massive flirt but she's not superficial (Even if she acts it). She has the shortest temper of the three of them and is less concerned about hurting people than her older siblings. Joanne tends to be more controlled and Kira has had years of training to keep herself in control so it's no real surprise that Thalia is the one that loses her temper and attacks Tomas in that way. Thalia also took the loss of Arianna and the crippling of Lysander probably harder than the others, or, at least, has not come to terms with it like her older sisters have. She ran away to essentially join the circus, after all.