I'm fairly sure this could be arranged for. As in, if there's too many of them belonging to the character set of a particular language, then it's very likely that it's simply a text in that language. But random characters in the middle of ASCII identifiers are probably not something that you want.
Yeah I'm not opposed to adding highlighting to them, and we are investigating how to do it, but it was less clear-cut than the bidi characters (which are totally invisible when rendered). I think we'll want to make it a bit more configurable and probably a separate option to the one which highlights the bidi characters.
