Enterprise ticket to Pearse Street

[aWotW]

Occasionally on the Enterprise when approaching Dublin Connolly the train manager announces that
"your enterprise ticket is valid for onward travel on the Dart to Tara and Pearse"
I can't find that in writing anywhere on the Translink or Irish Rail Websites.
I don't suppose it is documented anywhere?

When I buy a ticket in Newry, it says to "Dublin CIV"
I have not been to Pearse in a while but I remember it has ticket barriers on the way out.
If I were to get off the Enterprise in Connolly and get a Dart to Pearse,
I assume to get out of the station I am going to have to show the ticket to someone in order for them to let me through the barriers.

Does anyone have experience of that?
Is there always someone at the ticket barrier?
Are they likely to look twice at a NI Railways ticket from Newry?
Or might I have to explain that they said on the Enterprise I could use it?
I'd feel better if I had it in writing.