Hello!
It seems, wsprintf() / wprintf() are not working in musl as expected, if uses with cyrillic:

C testcase:
#include <wchar.h>
int main() {
  wprintf(L"[hello]\n");
  wprintf(L"[Привет]\n");
 return 0;
}
on x86_64-linux-gnu prints:
[hello]
[Privet]
and on x86_64-linux-musl prints: [hello]
[

There are other cases described:
https://github.com/emscripten-core/emscripten/issues/11947