The separate data taken by JB blows the clerical error theory - unless she made the error and tried to keep notes to make up for it. But I doubt it. She would have reported it to her supervisor I think.
Either way, I suspect the intention of management is to get more cheap options before they plough forward. The CA is one excuse. There are many excuses.
So out of laziness she decides to keep a secret journal of notes? And that happens out of the blue? This journal was just sitting there waiting for anyone to use it or did she take the time to go buy it? Sounds like the opposite of laziness to me