There's the file and here the wall textures.
Problems occurred with the cache settings. Persistent cache was used to achieve stable lighting over all frames with indirect cache. That didn't work perfectly, there is slight flickering.
Caustic cache was also used for better reflections, the light is placed inside one of the acrylic octrahedra so that all the light in the scene is from caustics.
Now what happens when indirect and caustic caches are used with persistent and periodic settings?
I had assumed that persistence would work for the indirect cache and the periodic setting would override persistence for caustic cache with only the first samples read from the saved cache.
As it turned out there are white dots within the acrylic bodies appearing stable in the animation.
That looks like caustic cache revolving didn't work because it would show random changes in each frame.
Also I accidentally left the step side too high at 15, but that would be obsolete when revolving doesn't work anyways.
Those white dots, being SDS-cache artifacts, somehow look like small bubbles and quite realistic though I was aiming for clean glass look.
Of course I rerendered single frames after the animation was finished and got somewhat better results but finally decided not to rerender the whole thing.
The persistent cache was rendered from an extra frame not in the file with the camera in the middle between the floors, no tilting up and a wider field of view catching the whole area.