That is correct, I would say, it is not a problem to an experienced bellows builder, but for a green hand that could lead disaster at folding.
I would suggest keep one rib tip for each pair, so it would be easy to follow when folding.
In my example, shape A would be the sides for up and down side, and both inner layer and outer layer will leave seam at this shape, leaving tips at this side would be better.
When preparing the rib pairs for shape A, follow the shape outline instead of inner line as Post 6A instructed, so we have space to trim the tips.
Best draw slant lines as trimming guide, every other rib has the same trimming angle, so if you did not mark them, it will be easily do it wrong.
As image shown, I mark every other rib, to remind myself when trimming.
After trimming, let's layout all four side of rib pairs, you can see the difference now, comparing with the way previous mention in Post 6B.
This will help providing enough hints when folding bellows.