Shaved Doubloons

The answer is easy. Attack every town

32 doubloons times 12 towns is 384 and the grams don't matter

Now you are just guessing. Can be done in less than 10 weightings.

Even if each town gave less than 1 coin then that would still be 12
I don't get it.

I'm not going to reply to all your comments cos i was wrong in a lot of them but i got a few.

No worries. This one can be done in merely two weightings.

But what if the other ten were cutting bits off of their coins?

You can tell exactly which towns are shaving bits off in two weightings, no matter how many of the towns are doing it.

Two weighting a of each town? Or two in total. What if the first two were fine and then the rest aren't?

Two weightings total.