CONCORD kills appear on zkillboard.
Additionally, gank ships that die to CONCORD, around the same time that an incursion fleet dies (these losses also appear on zkill) should easily show in the ‘Related’ link, which shows losses in the same system +/- 1 hour. Any logisitics ships should also show gank ships on their lossmails in the same ‘Related’ losses link.
So it should be simple to show it happening if it has. I’ve looked. Can’t find them. So when?
click this link: https://zkillboard.com/kill/57214298/
Then click the ‘Related’ link: https://zkillboard.com/related/30001675/201611170500/
Basically, an entire incursion fleet lost. However, the logi have no gankers at all on their lossmails, so this isn’t an example of the type of thing you are claiming. There are also no ganker ships lost in that 2 hour period in the system. So it isn’t one of your examples (though not all gankers are linked on zkill, but the logi losses should show their ships, in which case they will show anyway).
So there should be easy to demonstrate examples if this is a thing beyond theory.