These problems are intrinsic to the languages; they are not problems with Unicode. The real solution is political and cultural: if using strings across languages is a frequent use case, that use case can only be addressed by harmonizing the writing systems themselves and adapting real-world usage; it's not something that the encoding can solve.
I don't follow what you are trying to say. Are you saying the Japs and the Chinks should unify their writing systems? Because that's as disrespectful as the demonyms I have just used.