Hey GR_Nonsense,
That just means if you still have access to the original EA account where that progress was made, re-linking the platform there may restore access to the content. Unfortunately that cannot be guaranteed as the process of unlinking an account can cause permanent issues in some cases.
If this is the original EA account and you've re-linked your PSN account here but that progress has not returned, unfortunately that would mean it's lost. If you're not certain this is the original account or you no longer have access to the original EA account, our support team can help verify and update the login information for the EA account itself, however sadly they would not be able to manually restore anything that hasn't returned from re-linking.