Hi Oleg, hi Heinz,
I wish I could really help. For me, the same happened. It's the same exhibition, even with the same iframe (the Ukrainian instance references the Kyiv instance for embedding there). But the tour in kyiv.ua... was distorted indeed.
After I pressed CTRL+F5, the distortion was solved. I'm really more of a backend person at heart, so I can only guess. But maybe it might be something in the direction of a bug in pannellum related to the initial scroll position from where the tour was started?