I seem a bit late to discovering this Irish choral group. Having posted Pentangle’s 1969 single recording of ‘Once I Had A Sweetheart’ here a couple of days ago, YouTube’s algorithm threw up this 2023 live performance of the same song, clearly based on the ‘Tangle version. It seems to be Systir’s only studio release so far (a digital single). I find it mesmerisingly good. (video in comments)