You have to call eBay Support and go fukushima on them. Usually, if the packages were delivered to the buyers on-time they'll remove the defects. At least that's what they've done for me, for most of them. It's the few packages that USPS delivered late or didn't scan on delivery that became "bullet points" upon impact... In those cases, you have to pull the full tracking history and argue the delay point(s) in the chain.
As for "proof" of collection, as far as automated-eBay is concerned, a SCAN is the only proof of collection. If you're not, then you need to print the scan form when purchasing labels. If you are, then you need to have it out with USPS for not scanning the form upon pickup. I have timestamped video of evey package pickup but eBay doesn't watch videos.
Re fighting delays, for example, I had one shipment that wasn't received by the buyer for about two weeks because they kept their aggressive pit bulls loose in their fenced front yard, so the mail carrier fearing for his/her life wouldn't deliver the package, AND of course couldn't leave notice or even deliver other mail because the mailbox was on the front porch of the house. I called the buyer's post office and spoke with a manager, and asked her to send me an email with that information, plus any updates, then I used that to argue with eBay. She also updated tracking with "blocked receptacle" events, which is what I suspect helped the most.
I've had a few that were delayed because of forwarding to the buyer's new address; buyers, always remember to NOT change your shipping address in eBay/PayPal when you move so that eBay can "defect" sellers for late delivery.
And, for some reason, first class parcels in thin packages (envelopes rather than bubble mailers) seem to never get scanned until they reach the destination's sorting facility or the destnation post office, UNLESS they're on a scan form or I specifically ask for an acceptance scan.
And then there are the weather/event delays... Despite what eBay claims, that their "shipping team" is always on top of weather delay reports, they actually only track major events the carrier reports on; blizzards, hurricanes, volcanos, tornados, tsunamis, extinction-level comet impacts, etc. Otherwise, you'll have to match up tracking history with local weather/events along the package's journey.
(And YES, these are things I've actually researched and argued with eBay, mostly successfully. Birth and then 56 years of residing in NYC demonstrates that you either fight or die, especially when your opponent is City Hall, so it's in my DNA; I simply can't help it.)
