The labna worked out very well!
It's been draining in the fridge since around 9am this morning - so had about eight hours to firm. We taste-tested it late this afternoon, served on crackers with slivers of sun-dried tomato. As usual, Erin had hers drizzled with sweet chilli sauce.
I make labna at home from time to time but will try for more consistent production here, given a kilo of generic-brand cheddar cheese was $12 at our local shop. I haven't bothered to check for speciality cheeses!