What sort of floor is upstairs, carpet over floor, floor boards, etc... Underlay may work to a degree but it depends on how well you want the sound reduced. I can't see it being an acceptable solution as the thump will still resonate. Insulation between floors could work better when teamed with the underlay but would probably be invasive and you'd still have the thump's resonate.

Has the job been finished and the full clean done? If so, then yes it’s untidy and not right for a new job. Go back and have another talk to the builder.

Is there a reason you’ve chosen a nib wall instead of glass? Glass would open up the bathroom. I think your plumber will also change the location of your drain. And unless you absolutely absolutely love the long shower grate, I’d skip it. They drain into the same size hole as a standard one but add a larger area to clean and catch hair. I would also out the toilet between the vanity and shower. A toilet needs room on both sides but a vanity can go hard against the wall maximising the space.

Was the tiling done over new walls underneath? If so, it’s the builders job to make sure the wall is plumb and even enough to tile on. Is that a broken floor tile? That should not have been laid. There are applicable Australian Standards. They are available to the public but they cost, which is ridiculous but has been that way for years. I can’t post extracts due to copyright but you can Google. The AS2589 requires that the wall has less than 4mm of variance/bow across a 2 metres spread. You can measure this with a straight edge/spirit level. This is most likely the cause of uneven tiles although if it is isolated tiles the cause is probably too much/uneven adhesive. AS3958 requires that grout lines be even across the whole surface when viewed normally eg from the doorway with the light on. The width of the floor grout lines should be between 3-6mm depending on the type of tile used, and the wall grout should be between 1.5 and 6mm again dependent on the tiles. The same Standard requires the grout to be uniform in colour, smooth and without voids or pinholes. Be aware that removing tiles is likely to damage any waterproofing and that needs to be part of your discussion. Hope this gives you some pointers to discuss with your builder/tiler.