Short Answer: Yes
Long Answer: Blizzard has many, many times and in no uncertain terms labeled client asset modification as a bannable offense. Yes, even the purely aesthetic and non-gameplay changing ones. Why? Because it is not simple, realistic, or worth the development time to attempt to modify an anti-cheat system to determine if a client file modification is truly innocent in nature or not.
You’re going to get caught up in simply “You modified a thing, we told you to not modify things, now you’re banned.” situation. Definitely not worth.
The “maybe” is because I’m sure there’s certain key files they hold more weight towards and are more likely to ban if they see being tinkered around with, and such bans also tend to go out in “waves” so it’s not something you can immediately affirm as “safe” or not.