The info in GWadmin never gets updated unless you run an GWcheck with "audit report" on all PO's, only this will get the info from the PO's into the domain databases so does the info still show incorrect after doing this?

Yes, I ran the audit report twice, about a week apart and the admin console is still showing version 18.

We have a relatively small user base so we only have one PO.

Did you get an audit report? I suggest to open a case and send the audit.log to support.

I checked this and indeed version18 is showing, looking further the newer versions strings were not added in 23.4 

You can update to the latest gw24.2 as this had many changes in relation to this (additional fields were added) as we also show the build and client date etc now see the readme

www.novell.com/.../gw_readme.html

This is something , same client build and reported differently, I'm on 24.3 .

Looking into this as i seem to see the same in my lab using the latest 24.3 build

I created a defect for this issue, it is set to milestone 25.1 for now.