This would be very helpful.

It's not off-site - the link to CP, AFAIK, sourced downloads straight from here rather than transferring the files there for download. So the files were always here, on this site. And still are.

You have lists of those purchases. The difficulty is that people have different names. The cut-price option is to simply do all those people who have the same email address registered here as at CP - that could be done with a very short program. It's not all of them, but those who would require manual intervention would be a very small subset.

It would obviously involve some work and some costs, but goodwill is also usually rated as a material asset in assessment of a company, and therefore worth something.