Yeah, that would have got me too, most likely.
However, I have made a habit of looking at the power plug in let. It usually has a printed, or molded in diagram showing if it is center neg or pos.
I actually have not looked them up in manuals unless it is missing on the box itself, but I honestly can’t recall one without the info on the box.
Also, didn’t the PS come with 2 polarity reversing cables?
We’re they not enough, did you need an actual converter box of some sort?
Hope this pedal #4 works like a charm and is everything you want it to be.