VBscript actually uses the default code page of the user default locale which may not be the same as CP_THREAD_ACP. Also for locales that don't have an ANSI code page, such as Hindi, it falls back to UTF-8.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54003
--- Not sure how I missed the mixed locales case before. This time I made sure to run it in all of the TestBot's supported locales and it looks all good: https://testbot.winehq.org/JobDetails.pl?Key=130549