The part of this I am really struggling with logically is that this button occurs in the open message composer interface, where it evidently obvious what the next step is - sending the message. this is not a button on the UI to open up the personal message (they are not private messages), which looks like this:
I feel like asking for a default change over this is somewhat unreasonable when the admin custom text functions are there so admins can customize and change interface text to whatever they wish. You can use the verbosity settings to find the translation key to easily find the text string.
