Seeing that the Anglican Covenant is consonant with the doctrines and formularies of the Church of Ireland, the General Synod hereby subscribes the Covenant.
Using the word 'subscribe' rather than 'adopt' was important as a collective act of aligning. Quite right too: you subscribe to creeds and articles and doctrinal/ behavioural covenants or, in the case of my liberal Church, you don't.
The Covenant further comes under the Preamble and Declaration of the Church but means no change in doctrine nor, formally, its sovereignty. However, the South East Asians will understand this as accepting the movement towards a higher pan-Anglican authority and towards restrictions against who can be included within ministry and regarding blessings. If the Irish bless active gay relationships or approve gay relationship ministers, the Church will have some explaining to do towards the Communion - and this Covenant comes into being as Churches adopt it, not at some later date of formal declaration.
The Church of Ireland vote is hardly a recognition of the changes taking place in society throughout the island of Ireland. Clearly it puts pressure on the Church of England to adopt or subscribe to the thing: if the Church of England does not then the Irish will look a bit offshore.