Thank you for suggesting! I have moved this topic to "Feature Suggestions" section. We will add this to our improvements list. It will be announced in our roadmap or release note if chosen for implementation.
comment_form.ctp is used in more places I think (not sure, I didn't check it)... to fix that you need to change and modify one specially for "chatting", such as comment_form_chat.ctp and change <?php echo __('Comment'?> to <?php echo __('Send_chat'?>
and in translation file use:
msgid "Send_chat"
msgstr "Send"
and in translation file use:
msgid "Send_chat"
msgstr "Send"
It fixed on 2.4.1.
Thanks,
Kent,