What is the 'continuous standard load' of a battery?
If I operate at say 10mA, will that translate to something much lower than 225mAh?


Certainly, yes. I'd even say you should find a different battery for your application, as CR2032 is not suitable for such high currents.

Take a look at the following graph from your datasheet:



Even at 1.5mA, you're going to lose between 12 and 33% of nominal capacity. The cell wasn't characterized at 10mA, but extrapolating the graph I'd say you'd be lucky to get 30-50% of usable capacity in the optimistic case. Realistically, the cell may simply fail from overcurrent after a few hours of continuous 10mA load.