I suggest we wait to deal with DB names until we also have a way to deal with filenames. And this time test that it works is practice:-) Hopefully users and programmers will only need one method of handling non-ASCII LMDB names on Windows, not two.
I'd be nice if 'mdb_stat filename -s dbname' would Just Work, as would reading DB names and filenames from an config file. Yet OS-aware and OS-specific config files can look rather different. Maybe LMDB must handle DB names more flexibly than filenames, or maybe we'll end up recommending that "portable" DB names must be UTF-8. And add a "flag convert UTF8<->WCHAR if this is Windows".