I have found an android apps that uses Cling, (a fork of it, I guess), in its cling terminal unicode characters can be written, but in a strange way (when you press an unicode character key, it deletes a back character (prompt’s etc.) But if its difficult, it can be written at least. Is this from this apps’ cling code’s difference or from android platform’s specifications, I cannot know really. Maybe it helps to this issue? (Apps name is cxxdroid).
Thanks for your kind interest.