I found this video on YouTube while looking for some which had Muirgen singing in them. This was recorded only last year and sees her and Irish tenor Killian Donnelly performing All I Ask of You from The Phantom of the Opera, accompanied by the RTÉ Concert Orchestra. Killian is no stranger to the genre of musical theatre - he has appeared in various musicals and plays such as Les Misérables, The Phantom of the Opera, The Commitments, Memphis and Kinky Boots.
From what you hear, Muirgen is very operatic - when she was announced as the new member it was noted that she trained as a classical soprano - and extremely beautiful. All I can assume is that she's going to make a great Celtic Woman member!
https://youtu.be/dT4C3-JEywI