Hi,
This is done on purpose. When an order is created the coupon number of uses is incremented. And the coupon number of uses is never decremented.
That's to avoid the customer creating several orders with the same coupon and then paying them when he wants.
That's because once the order is created, there is no way for you to stop someone from paying for the order.
And thus, when HikaShop receives the payment notification and confirms the order, it's already to late to say that the coupon has already been used for another confirmed order.
I didn't understand your sentence
On my coupon when I cancel or refund an order, the status of the coupon pass from 1 (1 left) to 1 (-1 left) and can't be re-used.
When the order is refunded, the coupon number of uses is decremented by HikaShop. So the customer will be able to use again the coupon code.