Meant to add…. I think he has to do that, as to cut it by like 5” to make that corner flow at approx 16”, one full tile would fit next to it, and then there’d be like 2, maybe 3” of spacing to fill, which would be really short. So I am thinking this is correct due to that? Is that the best way?

Bigger issue is what did he use for waterproofing at that cement board is not waterproof nor is it installed properly?

What millworkman said, tile backer board is not prepped properly, have him read manufacturer installation instructions.

I am using a plumber that brought me the guy doing the tile. He said he was going to use wonderboard, which I thought I had read was waterproof if you get a certain thickness? Is that incorrect? What a mess if so! Thank you for your input

There was some kind of black wrapping done too that’s under that board. He said he was installing waterproof oil paper and then the wonderboard. Is that better?

Thank you so much, I really appreciate your input and will speak with the plumber. Any additional thoughts on the tile?

Addtl photo

I'm not sure what he plans to do at the transition point there, right now it looks "hacked-up"... Tile backerboard usualy butt's flush with the drywall and it will over-lap the drywall and have a nice finished edge using n end cap tile, etc.

You will have to ask him how he plans to finish this and you should ask your tile installer, and not a plumber.

With that said, and with everything I see on the images you provided, I would get in there a professional tile contractor and have him take a look at all this or you will have some issues down the road.

Good luck.

"Any additional thoughts on the tile?"

Unfortunately tile does not matter at this point if the prep underneath the tile is not correct, It needs to come out regardless.

He hasn’t gotten too far; they are both at my home tomorrow and said they can tape all the joints and cover the exposed nails, that seems to be the only issue from what I’m understanding. They did use the waterproof oil paper underneath and he assured me this was the water resistant cement board. I plan to discuss the tile placement too though I’m not we’ll versed in what is right and what is not right

"said they can tape all the joints and cover the exposed nails"

But what about the joints and screw holes behind the tile already up?

What millworkman said and the bottom to about middle is the most crucial area.

The tile in the corners should be folded. A full tile could end in corner as another full tile starts at the corner on the side wall. The following row would have 2 half tiles. Basically the exact opposite of what was done on your project.