Well I'm 55 chapters into it and can say it didnt end up grating at all, mostly feels natural in a 'she's just 5 years old' kind of way and doesnt veer too much into 'she's meant to be 5 not 1' territory.
I also like the fact that Yotsuba isnt always happy smiley go lucky, but just like any 5 year old, makes mistakes and cries when told off or isnt allowed to do anything she likes.