There exist service providers that provide access to the records maintained by the Companies Registration Office for a fee (that this data is not available free to the end user is a disgrace, but not surprising in this kakistocracy).
I came upon this entry on the record for Irish Rail:
From my limited legal knowledge, I understand that the Plantiff is the person/entity initiating legal action (the person/entity on the receiving end of a legal action is the defendant).