From limited testing, it would appear that the message "Your chat will be created when it's approved by the moderators." pops up after creating a chat, only if the user chose to notify the group about the chat.
Also, moderators do not seem to have any option to approve or deny a chat. What moderators can do, is to approve or deny the *notification* that is sent to the group. Rejecting or deleting the pending notification message does not affect the chat. A chat always exists as soon as the user tries to create it (right?).
So, it would seem that the message "Your chat will be created when it's approved by the moderators." should be changed to "The group will be notified of your chat when the moderators approve the notification."