[numpad0]

At least touching Unicode strings in wrong locales only mildly corrupts the strings. Plenty of Win32 apps would crash if the system locale is in UTF-8.

[throw1234567891]

UTF-8 is a character encoding and therefore it cannot serve as a locale. There is no UTF-8 language, punctuation, date and number formats…

[numpad0]

I mean, UTF-8 string handling is language (of the given bitstream, not necessarily the system) dependent, e.g. Turkish lowercase I, Chinese Hanzi vs Japanese Kanji at same codepoints, etc etc...