@JQ I am not a seasoned veteran. I do have a resource to offer you though. In this book in traditional Mandarin, 郝廣才, the author, has a section about the importance of feedback from children.
https://www.books.com.tw/products/0010340040
There're also interviews with him online where 郝廣才 discusses how he implements feedback from children during the process before getting a book published. I remember him talking about having the children tell you the story by looking at the images without the text. If they leave parts out or get confused then you know you need to change something. I think children will be able to understand your line drawings and will appreciate them without the rendering.