True would've preferred some actual wholesome time with a (extroverted) baby and her brother, who didn't have ulterior motives. Her being an extrovert can be the reason why she isn't scared. Like how some babies laugh when u try to scare them.
Please explain your point in more details.
Perhaps you’re expecting her to be like Lady Baby mixed Little Goku??
Well I can say they should have made her personality consistent. She's smart enough to think up a plan to attract her brother, but shes intentionally made stupid when poison comes out of nowhere in a family where they are trying to kill each other. It's so obvious they regressed her thinking in order for the developments to happen.
She not that bright for her mental age. Really don't know what the point of making her transport from other world, yet making her acting like an actual baby tbh.