Hi Trevor. Can you confirm if you're currently on the Jive-x cloud version or is this Jive 8/9 single-tenant hosted? If cloud, then I don't believe that messaging can be altered. Maybe you can share a bit more on what you were looking to change based on the use case?
You might also want to post this within your support space instead or potentially a product feedback area. Since it's technical related, this best practices group might not share the same kind of developer expertise as some other areas.
As Billy stated you lose some flexibility with Cloud. I think a phrase substitution would allow this on a Hosted version of Jive.
On a related topic, go vote this up: Feature, Configuration, and Reporting Parity between Cloud and Hosted