I managed to get this to work with the help of a colleague.
This is a pretty bespoke problem but essentially the category array was re-wrote with a filter applied to only display current language within the document finder page template.
It also required the WPML Language URL format setting to be set as ‘different languages in different directory’s’
On a side note, it appears i’ve been blocked from visiting the ‘help.govintra.net’ site with a 403 error. Is there a reason my IP has been blacklisted? I can load the site fine via VPN or on my home network.