You say that Hebikawa has had character development, but she really hasn't. She may have depth to her character, and an interesting backstory, but she has not developed much at all. We have gotten to know her, but a key part of character development is change, and character growth.
I'm not gonna quote your enitre post, but it's odd to accusing me of not understanding the term character development because I didn't use it correctly when I asserted that Hebikawa had character development. Because I did not even use the term character development with reference to Hebikawa.
With that said, your point about the meaning of the term character development is inaccurate.
Character development doesn't require character growth: the reason we have those two different terms is because they mean two different things. Character development simply requires a character to be well-rendered on the page. Sherlock Holmes is a relatively static character, but he has great character development.
Villainous characters are the most common examples of "great character development without any character growth" -- Hannibal Lecter, for example, is a wonderfully developed character who does not experience character growth throughout the course of the books.