Firstly, the new emojis are not actually stored using that code. That are actually stored as the native emoji character e.g. 😍 so the replacement string would be that rather than :heart_eyes:.
Secondly, there’s little point in making potentially risky replacements. We’d just recommend unchecking the “Display in editor” option for the smilie.
It will continue to display as it is now, but users won’t be able to see it in the editor anymore.