The first one is in bidding. It's probably not really a bug, but it seems GIB's hand evaluation isn't well-defined.
My table:
Maybe my bid wasn't perfect, but at least it's a good slam. BTW, I should mention a minor problem here. 5♥ is asking queen and doubled, then what's North's redouble mean? I think it should be DOPI, showing no queen. But GIB says it showing ♥A which I think it's not very reasonable. (This hand has no queen just by accident)
However, which I mainly want to show is my opponent's table. When the challenge finished I saw my opponent stopped in 4♠, but when I saw what happened, I was shocked.
We know, 3♠ is limit raise and should be stronger than 2♠. How can North have some slam interest after 2♠, but no interest after 3♠???
=========================================================
Now the second hand. It's a very silly defensive error I think.
The third trick totally shocked me. East shown stopper, so I can't lead ♦A and instead choose ♦7. North surely should know ♦ are all good, but how can North didn't take third trick and save the contract from down 4 to made? Can North think I was dealt ♦9? But if so, I should play it earlier to avoid blocking. This is totally undesirable for us.
=========================================================
Looking forward for explanation and maybe further repairs. I created diagram here because I forgot how to post link directly, but they are absolutely true deals, I swear.