Yes, ‘composer message’ is the right term for the messages that appear.
The only way I know of to see the list of composer messages through the UI is to go to Admin / Customize / Text Content and enter education into the search box. This works because Discourse prefixes the key that is used in the composer message translations with education.
Searching for education will return a few extra hits, but it’s fairly clear which of the results are used in the composer messages.