If the redacted part was somebody's name or a project codename, there's basically no way to infer that unless the system has had source text with that info. But I guess in the case where they are redacting something like a "method or procedure" that has been written about unredacted in other contexts and then its application in this context is classified, I think that would be possible. I'm sure people are already thinking about how to guard against this.
Your second paragraph is interesting. It's basically an automatic disinformation generator. I think there's almost more security value in releasing a document like that with faked interpolated text standing in for redacted sections, and then a few blacked out sections to add to intrigue and credibility, than in doing a regular redacted document...but maybe there's benefits of the old way I don't understand. Not sure if I got what you were saying there, but I think I got your meaning correctly.
Your second paragraph is interesting. It's basically an automatic disinformation generator. I think there's almost more security value in releasing a document like that with faked interpolated text standing in for redacted sections, and then a few blacked out sections to add to intrigue and credibility, than in doing a regular redacted document...but maybe there's benefits of the old way I don't understand. Not sure if I got what you were saying there, but I think I got your meaning correctly.