[def4d]

I'm maybe wrong, but start by desaturate the red tiles, and don't use wall as white as you did
For the glass, put your abe=200, and use a plane emitter instead of physical sun, it's faster
Maybe make your windows as thin as you can for the unwanted glossi that should be resolved with the next release

[Mihai]

It's been acknowledged several times there are issues with the current version of Maxwell and sky when trying to make caustics. It takes a very long time and there are also some limitations.

Since you can't really see any reflections there, why not just remove the glass? You can fake some reflections later in PS.

[def4d]

Water is from the photo!