To show or synchronize these files which have non-English characters in file name correctly, your FTP server must support UTF8 mode. e.g. Rock FTP server, File Zilla server...etc.
In the most cases, FTP Synchronizer can detect this feature automatically. But some FTP servers don't report this feature correctly, but it's supported actually. If so, you can try to enable "Force UTF-8" option on "Profile Wizard->Advanced->Connection" and try it out.