Okay, I can sort-of see how Misaki can be considered timid due to being very shy around people and very insecure about her physical appearance, but I really fail to see how Luna, Tamaki, Leifang, or, heck, Fiona even, are even remotely timid. The first one was at worst eccentric and barely is even aware of other people, slightly out of it, and clueless enough about social graces that she at one point walked in openly while barely even wearing a towel to ask Momiji to rub ointments on her back while she was entertaining the Owner, causing her to nearly have a heart attack; Tamaki outright flirts with the owner and has an obsession with fondling breasts; Leifang… you're kidding, right? Leifang's "timid" (especially after she exploded at the Owner, to say little of what she's like in past games)? And, heck, even Fiona, whose entire characterization essentially amounts to a massive crush on the owner, literally snuck out of her castle and managed to somehow arrive on the Venus Islands by herself (and one of the gravures and episodes even implied that she was sheltered enough to actually be unaware of how large the world was, and apparently not hear about black-tailed gulls, mistaking one for a cat, and you have to admit, to do that takes a lot of guts), not exactly my definition of "timid" (when I think of "timid", I think of PJ from Goof Troop, Flounder from The Little Mermaid, heck, Luigi from Super Mario Bros., even, not to mention the Cowardly Lion). And I'm not even getting into the Xtreme 3 cast regarding whether they are timid or not.
As far as Nagisa, well, I've never really been a stickler for tsunderes (Misty mostly was a very tame version overall), but I will give her chops, at least she was given a slightly more understandable reason for not liking the Owner compared to most (Love Hina cast especially, in particular Naru Narusegawa and Motoko).