Overwriting an East Asian wide character with a narrow character:

中国 ESC [ 2 D x:
中国x

xxx中文 ESC [ 2 D x:
xxx中文x

Overwriting an East Asian wide character with a narrow character, in the middle
of an 80-column line with mixed narrow and wide chars:

xxx[...]xxx中文xxx[...]xxx你好xESC [ 23 G y:
xxxxxxxxxxxxxxxxxxxx中文xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好xy

xxx[...]xxx中文。xxx[...]xxx你好ESC [ 23 G y:
xxxxxxxxxxxxxxxxxxxx中文。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好y