I understand Meyer's idealisation of Renesmee, I can accept the fast growth but making her speak perfect sentences and etc is just weird. If Meyer had at least given Renesmee a toddler-like mispronunciations, some tripping and toddler behaviour it would've made her much more lovable in some ways. When I was young I had no problems with Renesmee but as I grew up I realised how weird it is for a one year old to be so perfectly controlled and like an adult. Meyer could've made Renesmee empathetic, unusually controlled, eerie, "perfect", intelligent and etc while still allowing her to have normal baby milestones in an accelerated pace. Like let's say Charlie got a scratch and bled a bit and Renesmee points and tries to kiss it with a magic kiss or something, you know normal child behaviour. Or perhaps she plays with a rattle and accidentally breaks it and cries and probably needs comfort by her parents, something that likely Meyer would make idealised again but it would be cute. Or maybe Renesmee loving Edward reading her mind but when he prevents mischief (honestly I don't know if Meyer is capable of letting Renesmee even have such a thought) and when Edward prevents it she gasps and says something like 'da-da no hee!' (I don't know if that's the right spelling but hopefully y'all get it). It would be nice if Renesmee had been able to toddle, babble (like talk to Edward in baby language but he understands cuz mind reader), plays with Bella's hair, likes being thrown abnormally high, drinks warm blood from a baby bottle (an eerie image I know), wearing Rosalie's jewellery, giving a goodnight kiss, combs wolf Jacob I guess. The point is just you know baby or toddler stuff
It would've made her much more likeable and for reader's to bond, nobody wants an adult trapped in a baby's body. I have a nephew, he's a toddler and I love his mispronunciation's, babbling and etc, so perhaps I'm projecting but sincerely Meyer could've lessened up on perfection.
Making Renesmee age fast is I suppose makes sense actually but Meyer could've slowed her mind, emotions, speech, skills and etc to match her growing age. People hating the imprint and her name is one thing that I get, but I believe one of the reason's fans despite loving the story or characters or whatever they love but just can't connect with Renesmee is because she's just too creepy and "flawless" in narration, like that's one really boring child. Because Meyer had always planned for the baby to happen and that's fine, but she really missed the mark on making fans actually connect with the baby