You are right. It is a horrible install job and I feel for you. I know little about tile installation. I presume it is not easy to take out. I wonder though if someone who did such a poor job is capable to doing a better job or not the second time around?

I've seen much worse. I'd have to see the balance of the room and how the layout was done around the room. This might have been the compromise in the layout to make it look right elsewhere.

The left side of the corner is worse than the other ...maybe he can cut those tiles out ..then cut them better and install tiles that fit in a straight line then grout a straight line . ..
Don't pay him until it's fixed .

Here is a pic from far so you can see the balance. The corners are just so bad. And when I look at the details up close, I can see poor tile cuts that were filled with grout. I’m hopeful they will resolve this issue. I think I will go with a different tile look to try and avoid this from happening again.

Yup, the installer should've done a dry install (mock up) first to set the starting points.

On my screen your tiles look like fish scales.

They are textured glass tiles. Here is a close up