I can't tell from the picture whether the glaze has been applied around it. I mean corner tiles that are rounded on one edge and glazed around the rounding. That has existed for over 100 years.
Try googling "tw-Abschluss fliese" that's what I mean.
Yes, they are. Not perfectly even, but that looks more interesting that way. I also looked at the ones mentioned. Very pretty, but of course for a somewhat different area of use. Here is another picture from our large bathroom.