Sorry to hear about the leak.
In reviewing the thread, it was not clear how many coats of epoxy you put on (2 or 3)?
A few years back I built a low vat with plywood and epoxy. (Sorry no pictures.) I found that I was not comfortable with it until I put on more coats of epoxy than I expected to. I had to order more epoxy, pay for the extra cost shipping, do a lot of sanding, coating, and it took a lot of time. But, given how much all the rest of a system typically costs, it seemed to be worth it to reduce the risk of a leak. I have not had any trouble with it since I filled it. The extra coats provides peace of mind.
So, I would consider taking the time to add additional full coats over the remainder of the interior.