Yeah, unicode is a whole compatibility nightmare that I refuse to contemplate in the context of this shitpost. Don't quote me on this, but 30k 8-bit cells should be enough for anybody.
Luckily, you don't need Unicode, and we've endorsed the no-Unicode move in Brainfuck Enterprise Solutions. If one needs non-ASCII text, there always are ASCII encodings, like ArmASCII and romaji.