Personally, I think that the putdowns can mostly be described as just her humor/personality. Her and Wakka just have a weird relationship like that, imo. Kind of like the bumbling sitcom husband and his nagging wife. :p I feel like that's what the writers are going for, haha!
But her behavior WAS in fact changed by the baby, ChercheurObscur, but in the total opposite direction of this novel. In X-2, she's softened. There's an entire scene where she is nice and romantic with Wakka the ENTIRE TIME. Even admits out loud that she relies on him and trusts him!!! Very different than the Lulu we're used to, but I think it was growth based on the fact that the Calm has come and now she can let her guard down, emotionally and otherwise. She is able to love without fear of Sin taking those she loves from her. She can even have a child without fear of it being killed by Sin. So, she seemed much more at peace in X-2.
But in the novel, she seems to have regressed, based on this chapter, anyway. More relevant to our complaints, when Yuna returns to Besaid, Lulu just sort of jokes about how Yuna can "spread her wings", now that Lulu isn't there. No scolding. No yelling at. No "why are you wearing that"/"what are you doing"/"think of your IMAGE, yuna!!" I always took this to mean that Lulu was beginning to let Yuna grow into her own person. She was glad that Yuna was spreading her wings, and doing what she wanted to do, without fear of consequences. Because why wouldn't Lulu be? Lulu loves Yuna. She would want Yuna to be happy, wouldn't she? Even if that meant sacrificing her image or respect of the Besaid elders. S
It seems like regression of her character to make her suddenly be bossy and controlling of Yuna again, like Yuna is a little kid incapable of deciding for herself how she wants to handle her own affairs. It would have been one thing for Lulu to give Tidus a word of caution. That would make sense. But no-- she straight up gave him ORDERS on how to treat Yuna. That seems... meh. Like I said, character development regression.
I'm worried they are doing this to Yuna (regression of her growth), too, but I'm reserving my judgement until I read more of the book! She's barely been in one chapter. More on that later, maybe-- but hopefully not! Hopefully my feeling is wrong. xD
Rikku, on the other hand... I understand when she bursts about Tidus not listening. I can see RIkku being like "hey, I am the greatest storyteller ever and these are the most exciting awesome tales of all time, you should be grateful I'm even sharing them with you, why aren't you listening to me?!" and getting mad at him for being distracted. xD BUT... why the heck would she leave the party?! Rikku loves parties and gatherings!!!! She doesn't want to be at the banquet?
That's just weird and seems like an excuse for the writers to shoo her off to another place. Maybe she was trying to give Yuna and tidus privacy, but for one, they aren't getting any in the first place, and two, since when is Rikku considerate of that? l o l
And I thought her outburst about the Fayth that drew all the villagers attention was just weird??? But I'm guessing it wasn't supposed to be ANGRY, just passionate. If so, that makes sense, I guess... she's just trying to make sure that Tidus recognizes how much Yuna went through to get him back. They DID have their moments of teasing and joking around together like the friends they were in X, so that made me happy!