Strangely, this permission is dated 21st November, 2009, on the website of the Pontifical Commission Ecclesia Dei. Nice to see the Holy See ahead of the game!
Two video clips of the Gregorian Rite Liturgy in Mariawald have recently been posted on gloria.tv. The first (above) is the Preface and Sanctus. The second (below) is of the Pater Noster and Pax Domini.
There are five Trappist houses for men in Ireland and one in Scotland. None of them have sought or been given permission to revert to the Use of Monte Cistello - nor is it likely that they will. Those houses in Ireland are, in order of foundation, Mount Melleray Abbey (1832), Mount Saint Joseph (1878), New Mellifont Abbey (1938), Our Lady of Bethlehem Abbey (1948), and Bolton Abbey (1965). Sancta Maria Abbey is in Scotland.
There is one Trappistine house for ladies in Ireland, St. Mary's Abbey. It is equally unlikely to seek permission for the Use of Monte Cistello.