From a chemical perspective, yes it is safe. If you can get the green patina off the surface, then the copper will be fine chemically. This site seems to have a few good ideas of how to do it.
How Do You Remove Green Corrosion from Copper Pipes? - GoodBee Plumbing
From a mechanical integrity perspective, there may be issues. undiluted StarSan is a reasonably strong acid and the corrosion may have thinned out the walls of the copper pipes or even corroded through the metal completely. Some copper piping has very thin walls. You'll have to examine the entire affected area carefully, maybe use digital calipers if you have them to see if the pipe is noticeably thinner than unaffected areas.
If you are happy there are no holes, I'd conduct a pressure test. Find a way to shut off the outflow side, then fill it with water from your faucets to blow any air out the chiller, then close the outflow side and open your faucet all the way. Do it in a bucket in case there are leaks.