My mum's family come from Cornwall, not far from St Austell :)
I've always thought it would be a good boys name (maybe better as a mn, my combo is
William Austell), I never thought of it as particulary feminine.
As it's pronounced more like 'Awe-stul' though,
Stella seems a bit of a stretch, but it could work.
Lille is ok, again maybe better as a mn as people might confuse it with
Lillie.