What is likely happening is the towns people swearing a lot, filling their jars, trekking to the altar and donating it on your behalf.
Magic juice is then filled remotely so you don't have to return all the time, as that was repetitive in my play through.
Once you have saved about 2/3 of the town, it fills pretty constantly. Tweaking and balancing needed :)
I actually found very late that the release export would not work so I just opted to upload a debug build for the sake of getting a working build submitted. Also that the web export had issues as well, price I pay for using 4 RC1