In principle, it should possible to input non-western characters such as Kanji and Kana in the client GUI, for example as username, or as an exported file path. At least on my machine, this does not work correctly. I have iBus with "Anthy" activated. The input method overlay window and character selection works correctly. However, after pressing Enter, I'm left with "box characters" in the client. This is true for our tlclient.bin and also the FLTK test programs such as "editor". This is likely a font problem. Could be a configuration problem with my machine, but it works correctly with all other applications I can find, such as Firefox, Libreoffice, gedit, knotes, xterm, jconsole (Java). So my guess is that FLTK at least needs some tweaking wrt font selection.