I can speak to the chiller design as it is. There are reasons for choosing a cooler. It is insulated. The double wall construction allows for it to be fastened to the plywood with short screws from underneath that do not pierce the inside layer. I had originally wanted to make the tub with painted plywood but was overruled as seams can become leaks. The cooler is also the right physical size and not brittle. Single wall totes may be difficult to source in the right premade size and they are either too flexible or too brittle to use. If you choose to replace the cooler with a different container you will be right back to the same issue, sealing around the lines.
Least effort option would to pick the old silicone off, dry the area with a hairdryer, and replace it with new silicone. This is the second one of those that I’ve built. There is a lot more work that goes into it than it seems. The next steps with the chiller were to install high and low level sensors (we have them).
If someone wants to replace it with another one my feelings won’t be hurt.