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I'd like to have a closer look at the wall/tub junctions there.
That sort of tub is not normally intended for use in a shower and I'd like to see how the drainage appears at the horizontal surfaces.
That won't, of course, tell us anything at all about the even more important waterproofing treatment at those junctions.
As for the maintenance of the shower surfaces, all I can say is I'm certainly glad I won't be your maid. It's prolly beautiful (from what I can see in your photos), but I can't imagine actually having that for a regular use shower even if I could afford a maid.
My opinion; worth price charged.