Lack of Unicode support in file names / paths

[codicusmaximus]

Cannot transfer files with Japanese characters in the path on Windows running with English as "default language for non-unicode applications". This indicates to me that file paths are ASCII instead of Unicode.

[ghost]

Same here with Russian/Ukrainian characters, except maybe that files actually transfer, but without any name or extension.
Language for non-Unicode programs is Russian.
OS: Windows 8.1 (64-bit)