I haven't been there, but I'd expect the tendency to swirl in any particular direction to be created not by the Coriolis effect but by any imperfections in the sink/basin/bath waste and/or tilt (i.e. not being level). In other words, I'd expect it to be arbitrary.
water does not swirl different ways depending on which hemisphere..
many try to explain that it does by using "coriolis force" which says that in the northern hemisphere, things further north move slower than things further south causing a clockwise rotation..
in reality, this is only visible on a massive scale in some weather paterns and would not affect a mass of water so small..
You sure this isn't the old sphere of radius r, inside a right cylinder which has a height 2r and internal radius r ?
Shove a right cone in that cylinder with base radius r and height 2r
Then we get...
Cyl' vol....... 2 Pi r³
Sphere vol.. 4/3 Pi r³
Cone Vol.... 2/3 Pi r³
There then exists a simple volumetric relationship.
cone : sphere : cylinder .... 1 : 2 : 3
I cannot place the direct relationship between your cone and sphere touching it internally without the cylinder connection and common radii.