Wait, the guide had a picture showing a different spot than the written instructions? That's actually wild! I would have trusted the text over a picture too, no question. How does a published guide get that so backwards? It makes your whole freak-out make perfect sense, you were following the wrong clue!

Have you actually tried rapid-set in mud before? I've used it on wet jobs and it held up fine if you prep the area right. Just gotta get most of the water out or use a mix with extras for damp ground. Rushing isn't always bad if you know the tricks. Your method works, but from my view, fast concrete can be a lifesaver on a tight schedule. It doesn't automatically wreck a job.