"Doesn't help anyone not from The Northern Isles with the lyrics though!"

The Shetland dialect is a dialect of Scots, though it is heavily influenced by the former Norn language, however if you are used to reading a bit of Scots (which I know not everyone is) then there is nothing too inaccessible in this particular lyric. The main thing that sets it apart is the use of "D" for "th" in the likes of "Da" which is just "the".

The spelling of "snaa" for snow is used in other Scots writing too. Interchangeable with for instance "snaw" as there is no set in stone standard for spelling.

attempted transaltion is

saw you the lass going up the hill singing
so light a young heart she knew no care at all
laughing and waving when her lad was leaving
the line boats of Deltin are sailing away

saw you the lass standing on the hill waiting
scanning the Firth where the west wind did blow
for now she is fearing the spray is tearing
the high hills of Deltin are covered with snow

saw you the lass going down the hill crying
when over the wild water the (homing) did draw
no more was she singing, the morning/mourning was bringing
the ill news to Deltin of them that's away

saw you the lass going over the hill leaving (ie moving house)
in the Firth there's no life, there's no young ones at all
no dances they're having, no fiddlers are playing
it's lonely in Deltin from when they sailed away


I put homing in brackets as I'm not sure but I think it probably just means homecoming. As with 'moarnin' which could be either morning or mourning. I'm not sure! For 'brae' I put hill though in this case I suspect it is specifically the slope from the land above down to the seashore

Hope it helps a bit