Hmm. I seem to be able to cat a UTF-8 file to my UTF-8 terminal and it works perfectly. Yet cat has no concept whatsoever of UTF-8 and quite likely is splitting the text into blocks right in the middle of UTF-8 characters! How is this possible?
UTF-8 is in fact trivial. You are basically doing exactly what I am complaining about: panicking that there is some magical problem with not looking for the character boundaries. Try comparing it to words: how much of a word processor is able to ignore word boundaries? Almost all of it. But that does not somehow make it impossible for word wrap and word deletion to work.
It's not rocket science. The problem is people who are so convinced it is that they complicate things to no end and are hurting I18N and everybody.