The splash "日本ハロー!" is incorrectly translated.
This is not intentional because other translations are translated correctly. Only Japanese is incorrect (at least I confirmed).
"日本ハロー!" means "Japan Hello!" and we do not use "ハロー" for "Hello", instead we use "こんにちは" which is pronounced "Konnichiwa" as you know.
So it should be "こんにちは日本!" instead.
This is not a working as intended feature, or a suggestion. It is a bug.
Linked issues
Comments

@unknown in MC-9488: