I checked, and it turns out there was only one actual failure, which has already been refunded. However, it took about ten minutes for the refund process to start, so it might have been hard to notice. All the other generations were successful, and you should be able to confirm this from the generation history on your profile page.
I've added a new page for detailed credit transaction history, so you can check it here:
https://muryou-aigazou.com/ja/credits/history?type=use&category=image&model=18
For refunded credit usage history, a small yellow "Refunded" label will appear, as shown in the image below.
I also added a filter by model and a timeline view that groups generations by date to the generation history on your profile page, which should make it easier to compare them.
