So its not possible to fix this? (Hard or Software with GoPros?)
In videos on http://www.airpano.com/
i dont see errors like this.
It's not as noticeable in videos.
Or maybe its a Problem in small rooms?
Parallax will be more of an issue where there's any part of the subject closer to the camera than perhaps 100m.
No, parallax issues cannot be resolved by reorientating the cameras unless all cameras are at the NPP (No Parallax Poiunt) which as I understand it is impossible with a multi-GoPro setup.
If your goal is 'still' panos rather than 360video then in my opinion you'd be better off with a single camera, a fisheye lens and a pano head.