Also, in light of everything that is happening, is incredible that the top comment on this thread is about some minor semantic definitions.
(A better analogy might be the original physical document with redaction marks. If the text is printed using a laser printer or a type writer, and the marker used for redaction uses some other kind of ink - let's say one that doesn't dissolve the text's ink or toner in any way - then you can in principle distinguish between the two and thus recover visibility of the text.)
Plain text and flat images are my preferred formats for things which must be redacted. Images require a slight bit of special care, as the example in the underhanded C contest highlights, but it's possible to enforce visible redaction and transcription steps that destroy hidden information.
If you say “they failed to redact data” to a layperson looking at a visibly redacted document they’re going to be confused.